Implantable Electroacupuncture System and Method for Treating Parkinson&#39;s Disease and Essential Tremor

ABSTRACT

An implantable electroacupuncture device (IEAD) treats Parkinson&#39;s disease or Essential Tremor through application of stimulation pulses applied at at least one of acupoints GB34 and GV20. The IEAD includes an hermetically-sealed implantable electroacupuncture (EA) device having at least two electrodes located outside of its housing. The housing contains a primary power source, pulse generation circuitry, and a sensor that wirelessly senses externally-generated operating commands. The pulse generation circuitry generates stimulation pulses as controlled, at least in part, by the operating commands sensed through the sensor. The stimulation pulses are applied to the specified acupoint or nerve through the electrodes in accordance with a specified stimulation regimen. Such stimulation regimen requires that the stimulation session be applied at a very low duty cycle not greater than 0.05.

RELATED APPLICATIONS

This application is a Continuation-In-Part (CIP) of U.S. patentapplication Ser. No. 13/630,522, filed Sep. 28, 2012, which applicationis incorporated herein by reference. This application also claims thebenefit of the following previously-filed provisional patentapplications, each of which is incorporated herein by reference:

-   1. VT12-002-01, Electrode Configuration For Implantable    Electroacupuncture Device, filed Mar. 6, 2012, Appl. No. 61/606,995;-   2. VT12-003-01. Boost Converter Output Control For Implantable    Electroacupuncture Device, filed Mar. 12, 2012, Appl. No.    61/609,875;-   3. VT12-003-02, Boost Converter Circuit Surge Control For    Implantable Electroacupuncture Device Using Digital Pulsed Shutdown,    filed Jul. 16, 2012, Appl. No. 61/672,257;-   4. VT12-004-01, Smooth Ramp-Up Stimulus Amplitude Control For    Implantable Electroacupuncture Device, filed Jul. 17, 2012, Appl.    No. 61/672,661;-   5. VT12-005-01, Battery Transient Current Reduction In An    Implantable Electroacupuncture Device, filed Jul. 19, 2012, Appl.    No. 61/673,254;-   6. VT12-006-01, Pulse Charge Delivery Control In An Implantable    Electroacupuncture Device, filed Jul. 23, 2012, Appl. No.    61/674,691;-   7. VT12-008-01, Radial Feed-Through Packaging For An Implantable    Electroacupuncture Device, filed Jul. 26, 2012, Appl. No.    61/676,275.

BACKGROUND

Parkinson's disease (PD) is a common disorder that affects the brain'sability to control movement. More than one million people in NorthAmerica have been diagnosed with PD, most of whom are over 60 years old.Parkinson's progressively worsens over time, although the rate ofworsening varies greatly from person to person. Many people with thedisease who are treated may be able to live years without seriousdisability. A number of treatments are available to help manage thesymptoms and improve a person's quality of life. However, there is nocure for the disease at this time.

Essential tremor is a disorder of the nervous system that causes arhythmic shaking or tremor. It can affect almost any part of the bodybut the trembling most often occurs in the hands and is especiallybothersome during the attempt to do simple tasks like drinking from aglass or writing with a pencil. Essential tremor may also affect one'shead, voice, arms, or legs. While it is not the same as Parkinson'sdisease, the tremor of Parkinson's disease resembles essential tremorand some of the same treatments, e.g., deep brain stimulation, are givento both disorders.

The cause of Parkinson's disease is unknown. (Note, throughout thisapplication, “Parkinson's disease” may be shortened to just“Parkinson's”.) Normally, certain nerve cells called neurons in thebrain make a chemical called dopamine that helps control movement. Inpeople with Parkinson's, these neurons slowly degenerate and lose theirability to produce dopamine. As a result, the symptoms of Parkinson'sdevelop gradually and tend to become more severe over time. It is notwell understood how and why these neurons stop working correctly.

The signs and symptoms of Parkinson's can be divided into motor andnonmotor. Motor symptoms are those that affect movement of the body.These are the most obvious symptoms of the disease. The main motorsymptoms of Parkinson's are tremor, slowness of movement (called“bradykinesia”), stiffness (“rigidity”), and poor balance (“posturalinstability” or “gait impairment”). These symptoms are usually mild inthe early stages of the disease.

Symptoms typically start on one side of the body and spread to the otherside over a few years. As symptoms worsen, a patient may have difficultywalking, talking, and performing daily tasks. While the symptomstypically progress slowly, progression varies from person to person.During the early stages of the disease, symptoms can be managed fairlywell with drugs.

The symptom of tremor caused by Parkinson's disease is the mostnoticeable when a person is at rest. The tremor of early Parkinson's isintermittent and may not be noticeable to others. Tremor usually becomesnoticeable one hand at a time, spreading to the second hand over aperiod of a few years.

The symptom of bradykinesia or slowness of movement eventually affectseveryone with the disease. It may result in feelings of lack ofcoordination, weakness, and fatigue. In the arms, bradykinesia can causedifficulty with daily tasks like buttoning clothing and clicking acomputer mouse. It may cause a patient to drag his legs when walking,take shorter shuffling steps, or have a feeling of unsteadiness. Aperson may also have difficulty standing from a chair or getting out ofa car.

The symptom of rigidity causes stiffened movement of the arms, legs, orbody. It usually begins on the same side of the body as the other earlysymptoms and similarly to other symptoms, eventually affects the otherside.

The symptom of postural instability deals with the failure of automaticreflexes that help a person remain balanced when standing and walking.The loss of balance or falling usually does not occur until late in theprogression of the disease. However, postural instability may require apatient to use assistance of another person or a wheelchair to getaround. Postural instability early in the disease state is suggestive ofanother Parkinsonism syndrome and not Parkinson's disease.

The nonmotor symptoms of the disease are those unrelated to movement.Many nonmotor symptoms affect a person's mood, the five senses, and theability to think. Problems with thinking and problems with memorycommonly occur in the disease and can range from mild to severe. Somestudies indicate that forty percent or more of patients are affectedwith these problems over the long term. Common cognitive symptomsinclude difficulty making decisions or multi-tasking, rememberingevents, and judging distances.

Psychosis, or the disorder of thinking that causes a person to losetouch with reality, occurs in twenty to forty percent of people treatedwith medication for Parkinson's disease. The underlying cause ofpsychosis is poorly understood, although many medications used to treatParkinson's can cause psychosis as a side effect, particularly in aperson who already has cognitive impairment. Visual hallucinations arethe most common symptoms of psychosis in Parkinson's and they oftenbecome more frequent and severe as the disease progresses.

In addition to psychosis, mood disorders such as depression, anxiety,and loss of motivation are common in people with Parkinson's. All ofthese conditions decrease a person's quality of life and worsen motorsymptoms.

People with Parkinson's disease also have sleep disorders and excessivedaytime sleepiness affects about 75 percent of people with the disease.It may be worsened by the medications used to treat Parkinson's. Somesimply feel sleepy while others experience sudden and unintentionalsleeping periods during the daytime.

There can be some autonomic dysfunction in Parkinson's with symptomssuch as low blood pressure after standing up, constipation, difficultyswallowing, abnormal sweating, urinary leakage, and libido dysfunction.

One's sense of smell is commonly lost by people with Parkinson's. Itusually happens early in the course of the disease even before many ofthe more familiar symptoms appear and it often goes unnoticed by thepatient.

Painful sensations are also reported by Parkinson's patients—by morethan 40 percent of patients. The pain can be piercing or stabbing,burning or tingling, and may be felt in several places or only inspecific areas of the body including the face, abdomen, genitals, andjoints. In general, painful sensations are experienced in the same bodyparts as the motor symptoms, and may be more prominent as medicationswear off.

The diagnosis of Parkinson's disease relies upon the patient's signs andsymptoms and not a blood or imaging test. Generally, bradykinesia (orslow movement) must be present to make a diagnosis and one of the twoother primary symptoms: tremor and rigidity. Other factors supportive ofthe diagnosis are: symptoms began on one side of the body; the tremoroccurs as the person's limb is resting; and the symptoms can becontrolled with Parkinson's medication.

An alternative approach for treating Parkinson's disease, and/orEssential Tremor and a host of other physiological conditions,illnesses, deficiencies and disorders is acupuncture, which includestraditional acupuncture and acupressure. Acupuncture has been practicedin Eastern civilizations (principally in China, but also in other Asiancountries) for at least 2500 years. It is still practiced todaythroughout many parts of the world, including the United States andEurope. A good summary of the history of acupuncture, and its potentialapplications may be found in Cheung, et al., “The Mechanism ofAcupuncture Therapy and Clinical Case Studies”, (Taylor & Francis,publisher) (2001) ISBN 0-415-27254-8, hereafter referred to as “Cheung,Mechanism of Acupuncture, 2001.” The Forward, as well as Chapters 1-3,5, 7, 8, 12 and 13 of Cheung, Mechanism of Acupuncture, 2001, areincorporated herein by reference.

Despite the practice in Eastern countries for over 2500 years, it wasnot until President Richard Nixon visited China (in 1972) thatacupuncture began to be accepted in the West, such as the United Statesand Europe. One of the reporters who accompanied Nixon during his visitto China, James Reston, from the New York Times, received acupuncture inChina for post-operative pain after undergoing an emergency appendectomyunder standard anesthesia. Reston experienced pain relief from theacupuncture and wrote about it in The New York Times. In 1973 theAmerican Internal Revenue Service allowed acupuncture to be deducted asa medical expense. Following Nixon's visit to China, and as immigrantsbegan flowing from China to Western countries, the demand foracupuncture increased steadily. Today, acupuncture therapy is viewed bymany as a viable alternative form of medical treatment, alongsideWestern therapies. Moreover, acupuncture treatment is now covered, atleast in part, by most insurance carriers. Further, payment foracupuncture services consumes a not insignificant portion of healthcareexpenditures in the U.S. and Europe. See, generally, Cheung, Mechanismof Acupuncture, 2001, vii.

Acupuncture is an alternative medicine that treats patients by insertionand manipulation of needles in the body at selected points. See, Novak,Patricia D. et al (1995). Dorland's Pocket Medical Dictionary (25thed.), Philadelphia: (W.B. Saunders Publisher), ISBN 0-7216-5738-9. Thelocations where the acupuncture needles are inserted are referred toherein as “acupuncture points” or simply just “acupoints”. The locationof acupoints in the human body has been developed over thousands ofyears of acupuncture practice, and maps showing the location ofacupoints in the human body are readily available in acupuncture booksor online. For example, see, “Acupuncture Points Map,” found online at:http://www.acupuncturehealing.org/acupuncture-points-map.html. Acupointsare typically identified by various letter/number combinations, e.g.,L6, S37. The maps that show the location of the acupoints may alsoidentify what condition, illness or deficiency the particular acupointaffects when manipulation of needles inserted at the acupoint isundertaken.

References to the acupoints in the literature are not always consistentwith respect to the format of the letter/number combination. Someacupoints are identified by a name only, e.g., Tongli. The same acupointmay be identified by others by the name followed with a letter/numbercombination placed in parenthesis, e.g., Tongli (HT5). Alternatively,the acupoint may be identified by its letter/number combination followedby its name, e.g., HT5 (Tongli). The first letter(s) typically refers toa body organ or meridian, or other tissue location associated with, oraffected by, that acupoint. However, usually only the letter(s), not thename of the body organ or tissue location, is used in referring to theacupoint, but not always. Thus, for example, the acupoint GV20 is thesame as acupoint Governing Vessel 20 which is the same as GV-20 which isthe same as GV 20 which is the same as Baihui. For purposes of thispatent application, unless specifically stated otherwise, all referencesto acupoints that use the same name, or the same first letter and thesame number, and regardless of slight differences in second letters andformatting, are intended to refer to the same acupoint.

An excellent reference book that identifies all of the traditionalacupoints within the human body is WHO STANDARD ACUPUNCTURE POINTLOCATIONS IN THE WESTERN PACIFIC REGION, published by the World HealthOrganization (WHO), Western Pacific Region, 2008 (updated and reprinted2009), ISBN 978 92 9061 248 7 (hereafter “WHO Standard Acupuncture PointLocations 2008”). The Table of Contents, Forward (page v-vi) and GeneralGuidelines for Acupuncture Point Locations (pages 1-21), as well aspages 188 and 213 (which illustrate with particularity the location ofacupoints GB34 and GV20, respectively) of the WHO Standard AcupuncturePoint Locations 2008 are incorporated herein by reference.

While many in the scientific and medical community are highly criticalof the historical roots upon which acupuncture has developed, (e.g.,claiming that the existence of meridians, qi, yin and yang, and the likehave no scientific basis), see, e.g.,http://en.wikipedia.org/wiki/Acupuncture, few can refute the vast amountof successful clinical and other data, accumulated over centuries ofacupuncture practice, that shows needle manipulation applied at certainacupoints is quite effective.

The World Health Organization and the United States' National Institutesof Health (NIH) have stated that acupuncture can be effective in thetreatment of neurological conditions and pain. Reports from the USA'sNational Center for Complementary and Alternative Medicine (NCCAM), theAmerican Medical Association (AMA) and various USA government reportshave studied and commented on the efficacy of acupuncture. There isgeneral agreement that acupuncture is safe when administered bywell-trained practitioners using sterile needles, but not on itsefficacy as a medical procedure.

An early critic of acupuncture, Felix Mann, who was the author of thefirst comprehensive English language acupuncture textbook, Acupuncture:The Ancient Chinese Art of Healing, stated that “The traditionalacupuncture points are no more real than the black spots a drunkard seesin front of his eyes.” Mann compared the meridians to the meridians oflongitude used in geography—an imaginary human construct. See, Mann,Felix (2000). Reinventing acupuncture: a new concept of ancientmedicine. Oxford: Butterworth-Heinemann. pp. 14; 31. ISBN 0-7506-4857-0.Mann attempted to combine his medical knowledge with that of Chinesetheory. In spite of his protestations about the theory, however, heapparently believed there must be something to it, because he wasfascinated by it and trained many people in the West with the parts ofit he borrowed. He also wrote many books on this subject. His legacy isthat there is now a college in London and a system of needling that isknown as “Medical Acupuncture”. Today this college trains doctors andWestern medical professionals only.

For purposes of this patent application, the arguments for and againstacupuncture are interesting, but not that relevant. What is important isthat a body of literature exists that identifies several acupointswithin the human body that, rightly or wrongly, have been identified ashaving an influence on, or are otherwise somehow related to, thetreatment of Parkinson's disease and Essential Tremor. With respect tothese acupoints, the facts speak for themselves. Either these points door do not affect the conditions, deficiencies or illnesses with whichthey have been linked. The problem lies in trying to ascertain what isfact from what is fiction. This problem is made more difficult whenconducting research on this topic because the insertion of needles, andthe manipulation of the needles once inserted, is more of an art than ascience, and results from such research become highly subjective. Whatis needed is a much more regimented approach for doing acupunctureresearch.

It should also be noted that other medical research, not associated withacupuncture research, has over the years identified nerves and otherlocations throughout a patient's body where the application ofelectrical stimulation produces a beneficial effect for the patient.Indeed, the entire field of neurostimulation deals with identifyinglocations in the body where electrical stimulation can be applied inorder to provide a therapeutic effect for a patient. For purposes ofthis patent application, such known locations within the body aretreated essentially the same as acupoints—they provide a “target”location where electrical stimulation may be applied to achieve abeneficial result, whether that beneficial result is to reducecholesterol or triglyceride levels, to reduce excess body fat, to treatcardiovascular disease, to treat mental illness, or to address someother issue associated with a disease or condition of the patient.

Returning to the discussion regarding acupuncture, some have proposedapplying moderate electrical stimulation at selected acupuncture pointsthrough needles that have been inserted at those points. See, e.g.,http://en.wikipedia.org/wiki/Electroacupuncture. Such electricalstimulation is known as electroacupuncture (EA). According toAcupuncture Today, a trade journal for acupuncturists:“Electroacupuncture is quite similar to traditional acupuncture in thatthe same points are stimulated during treatment. As with traditionalacupuncture, needles are inserted on specific points along the body. Theneedles are then attached using small clips to an external device thatgenerates continuous electric pulses. These devices are used to adjustthe frequency and intensity of the impulse being delivered, depending onthe condition being treated. Electroacupuncture uses two needles at atime so that the impulses can pass from one needle to the other. Severalpairs of needles can be stimulated simultaneously, usually for no morethan 30 minutes at a time.” “Acupuncture Today: Electroacupuncture”.2004 Feb. 1 (retrieved on-line 2006 Aug. 9 athttp://www.acupuncturetoday.com/abc/electroacupuncture.php).

U.S. Pat. No. 7,155,279, issued to Whitehurst et al., discloses use ofan implantable miniature neurostimulator, referred to as a“microstimulator,” that can be implanted for stimulation of the vagusnerve and used as a therapy (alongside drugs) for movement disorders.

Other patents of Whitehurst et al. teach the use of this small,microstimulator, placed in other body tissue locations, including withinan opening extending through the skull into the brain, for the treatmentof a wide variety of conditions, disorders and diseases. See, e.g., U.S.Pat. No. 6,735,475 (headache and facial pain); U.S. Pat. No. 7,003,352(epilepsy by brain stimulation); U.S. Pat. No. 7,013,177 (pain by brainstimulation); U.S. Pat. No. 6,950,707 (obesity and eating disorders);U.S. Pat. No. 7,292,890 (Vagus nerve stimulation); U.S. Pat. No.7,203,548 (cavernous nerve stimulation); U.S. Pat. No. 7,440,806(diabetes by brain stimulation); U.S. Pat. No. 7,610,100(osteoarthritis); and U.S. Pat. No. 7,657,316 (headache by stimulatingmotor cortex of brain).

Techniques for using electrical devices, including external EA devices,for stimulating peripheral nerves and other body locations for treatmentof various maladies are known in the art. See, e.g., U.S. Pat. Nos.4,535,784; 4,566,064; 5,195,517; 5,250,068; 5,251,637; 5,891,181;6,393,324; 6,006,134; 7,171,266; 7,171,266 and 7,373,204. The methodsand devices disclosed in these patents, however, typically utilize (i)large implantable stimulators having long leads that must be tunneledthrough tissue over an extended distance to reach the desiredstimulation site, (ii) external devices that must interface withimplanted electrodes via percutaneous leads or wires passing through theskin, or (iii) inefficient and power-consuming wireless transmissionschemes. Such devices and methods are still far too invasive, or areineffective, and thus subject to the same limitations and concerns asare the previously described electrical stimulation devices.

From the above, it is seen that there is a need in the art for a lessinvasive device and technique for electroacupuncture stimulation ofacupoints that does not require the continual use of needles insertedthrough the skin, or long insulated wires implanted or inserted intoblood vessels, for the purposes of improving the symptoms of or slowingthe progression of Parkinson's disease and Essential Tremor.

SUMMARY

One characterization of the invention described herein is an ImplantableElectroAcupuncture System (IEAS) that treats Parkinson's disease andEssential Tremor through application of electroacupuncture (EA)stimulation pulses applied at a specified tissue location(s) of apatient. A key component of such IEAS is an implantableelectroacupuncture (EA) device. The EA device has a small,hermetically-sealed housing containing a primary power source, pulsegeneration circuitry powered by the primary power source, and a sensorthat wirelessly senses operating commands generated external to thehousing. The pulse generation circuitry generates stimulation pulses inaccordance with a specified stimulation regimen as controlled, at leastin part, by the operating commands sensed through the sensor. The EAdevice further includes a plurality of electrode arrays (where anelectrode array comprises an array of n conductive contacts electricallyjoined together to function jointly as one electrode, where n is aninteger of from 1 to 24) on the outside of the EA device housing thatare electrically coupled to the pulse generation circuitry on the insideof the EA device housing. There is at least one cathodic electrode arrayand one anodic electrode array. Such electrical coupling occurs throughat least one feed-through terminal passing through a wall of thehermetically-sealed housing. Stimulation pulses generated by the pulsegeneration circuitry inside of the EA device housing are directed to theplurality of electrode arrays on the outside of the EA housing so as toflow between the anodic electrode(s) and the cathodic electrode(s). Asthe stimulation pulses flow between these anodic and cathodicelectrode(s), they are applied at the specified tissue location(s)through the plurality of electrode arrays in accordance with thespecified stimulation regimen. The specified stimulation regimen defineshow often a stimulation session (a stimulation session comprises astream or burst of stimulation pulses applied to the specified tissuelocation(s) over a prescribed period of time) is applied to the patient,and the duration of each stimulation session. Moreover, the stimulationregimen requires that the stimulation session be applied at a very lowduty cycle. More particularly, if the stimulation session has a durationof T3 minutes and occurs at a rate of once every T4 minutes, then theduty cycle, or the ratio of T3/T4, cannot be greater than 0.05. Thespecified tissue location(s) whereat EA stimulation pulses are appliedcomprises at least one of acupoints GV20 and GB34.

Another characterization of the invention described herein is anImplantable ElectroAcupuncture System (IEAS) for treating Parkinson'sdisease and Essential Tremor. Such IEAS includes (a) an implantableelectroacupuncture (EA) device housing having a maximum linear dimensionof no more than 25 mm in a first plane, and a maximum height of no more2.5 mm in a second plane orthogonal to the first plane; (b) a primarybattery within the EA device housing having an internal impedance of noless than about 5 ohms; (c) pulse generation circuitry within the EAdevice housing and powered by the primary battery that generatesstimulation pulses during a stimulation session; (d) control circuitrywithin the EA device housing and powered by the primary battery thatcontrols the frequency of the stimulation sessions to occur no more thanonce every T4 minutes, and that further controls the duration of eachstimulation session to last no longer than T3 minutes, where the ratioof T3/T4 is no greater than 0.05; (e) sensor circuitry within the EAdevice housing and coupled to the control circuitry that is responsiveto the presence of a control command generated external to the EA devicehousing, which control command when received by the control circuitrysets the times T3 and T4 to appropriate values; and (f) a plurality ofelectrodes located outside of the EA device housing that areelectrically coupled to the pulse generation circuitry within the EAdevice housing. The plurality of electrodes are positioned to lie at ornear a target tissue location(s) belonging to the group of target tissuelocations comprising at least one of acupoints GV20 or GB34.

Yet another characterization of the invention described herein is amethod for treating Parkinson's disease and Essential Tremor in apatient. The method includes: (a) implanting an electroacupuncture (EA)device in the patient below the patient's skin at or near at least onespecified target tissue location; (b) enabling the EA device to generatestimulation sessions at a duty cycle that is less than or equal to 0.05,wherein each stimulation session comprises a series of stimulationpulses, and wherein the duty cycle is the ratio of T3/T4, where T3 isthe duration of each stimulation session, and T4 is the time or durationbetween stimulation sessions; and (c) delivering the stimulation pulsesof each stimulation session to at least one specified target tissuelocation through a plurality of electrode arrays electrically connectedto the EA device. Here, an electrode array comprises an array of nconductive contacts electrically joined together to function jointly asone electrode, where n is an integer. The at least one specified targettissue location at which the stimulation pulses are applied in thismethod is selected from the group of target tissue locations comprisingat least one of acupoints GV20 or GB34.

A further characterization of the invention described herein is a methodof treating Parkinson's disease and Essential Tremor in a patient usinga small implantable electroacupuncture device (IEAD). Such IEAD ispowered by a small disc primary battery having a specified nominaloutput voltage of about 3 volts and having an internal impedance of atleast 5 ohms. The IEAD is configured, using electronic circuitry withinthe IEAD, to generate stimulation pulses in accordance with a specifiedstimulation regimen. These stimulation pulses are applied at a selectedtissue location of the patient through at least two electrodes locatedoutside of the housing of the IEAD. The method comprises: (a) implantingthe IEAD below the skin surface of the patient at or near a targettissue location selected from the group of target tissue locationscomprising at least one of acupoints GV20 or GB34; and (b) enabling theIEAD to provide stimulation pulses in accordance with a stimulationregimen that provides a stimulation session of duration T3 minutes at arate of once every T4 minutes, where the ratio of T3/T4 is no greaterthan 0.05, and wherein T3 is at least 10 minutes and no greater than 60minutes.

The invention described herein may additionally be characterized as amethod of assembling an implantable electroacupuncture device (IEAD) ina small, thin, hermetically-sealed, housing having a maximum lineardimension in a first plane of no more than 25 mm and a maximum lineardimension in a second plane orthogonal to the first plane of no morethan 2.5 mm. Such housing has at least one feed-through pin assemblyradially passing through a wall of the thin housing that isolates thefeed-through pin assembly from high temperatures and residual weldstresses that occur when the thin housing is welded shut tohermetically-seal its contents. The IEAD thus assembled is particularlyadapted for use in treating Parkinson's disease or Essential Tremor of apatient. The method of assembling comprises the steps of:

-   -   (a) forming a thin housing having a bottom case and a top cover        plate, the top cover plate being adapted to fit over the bottom        case, the bottom case having a maximum linear dimension of no        more than 25 mm;    -   (b) forming a recess in a wall of the housing;    -   (c) placing a feed-through assembly within the recess so that a        feed-through pin of the feed-through assembly electrically        passes through a wall of the recess at a location that is        separated from where the wall of the housing is designed to        contact the top cover plate; and    -   (d) welding the top cover plate to the bottom case around a        perimeter of the bottom case, thereby hermetically sealing the        bottom case and top case together.

Yet another characterization of the invention described herein is anImplantable ElectroAcupuncture System (IEAS) for treating Parkinson'sdisease or Essential Tremor. Such IEAS includes (a) at least oneexternal component, and (b) a small, thin implantable component having amaximum linear dimension in a first plane of less than 25 mm, and amaximum linear dimension in a second plane orthogonal to the first planof no more than 2.5 mm.

In one preferred embodiment, the external component comprises anelectromagnetic field generator. As used herein, the term“electromagnetic field” encompasses radio frequency fields, magneticfields, light emissions, or combinations thereof.

The implantable component includes a housing made of a bottom part and atop part that are welded together to create an hermetically-sealed,closed container. At least one feed-through terminal passes through aportion of a wall of the top part or bottom part. This terminal allowselectrical connection to be made between the inside of the closedcontainer and a location on the outside of the closed container.Electronic circuitry, including a power source, is included on theinside of the closed container that, when enabled, generates stimulationpulses during a stimulation session that has a duration of T3 minutes.The electronic circuitry also generates a new stimulation session at arate of once every T4 minutes. The ratio of T3/T4, or the duty cycle ofthe stimulation sessions, is maintained at a very low value of nogreater than 0.05. The stimulation pulses are coupled to the at leastone feed-through terminal, where they are connected to a plurality ofelectrodes/arrays located on an outside surface of the closed housing.The stimulation pulses contained in the stimulation sessions are thusmade available to stimulate body tissue in contact with or near theplurality of electrodes/arrays on the outside of the closed housing.

Further included on the inside of the closed container is a sensoradapted to sense the presence or absence of an electromagnetic field.Also included on the inside of the closed container is a power sourcethat provides operating power for the electronic circuitry.

In operation, the external component modulates an electromagnetic fieldwhich, when sensed by the sensor inside of the closed container, conveysinformation to the electronic circuitry inside of the closed housingthat controls when and how long the stimulation sessions are appliedthrough the plurality of electrodes/arrays. Once this information isreceived by the electronic circuitry, the external component can beremoved and the implantable component of the IEAS will carry out thestimulation regimen until the power source is depleted or newinformation is received by the electronic circuitry, whichever occursfirst.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the inventionwill be more apparent from the following more particular descriptionthereof, presented in conjunction with the following drawings. Thesedrawings illustrate various embodiments of the principles describedherein and are part of the specification. The illustrated embodimentsare merely examples and do not limit the scope of the disclosure.

FIG. 1 is a perspective view of an Implantable Electroacupuncture Device(IEAD) made in accordance with the teachings presented herein.

FIGS. 1A, 1B and 1C show front, back and side views of the head,respectively, and illustrate with particularity the location of acupointGV20 or Baihui, one of the locations identified herein for implantationof the IEAD for the treatment of Parkinson's disease and EssentialTremor.

FIG. 1D shows the location of acupoint GB34 or Yanglingquan.

FIG. 2 shows a plan view of one surface of the IEAD housing illustratedin FIG. 1.

FIG. 2A shows a side view of the IEAD housing illustrated in FIG. 1.

FIG. 3 shows a plan view of the other side, indicated as the “BackSide,” of the IEAD housing or case illustrated in FIG. 1.

FIG. 3A is a sectional view of the IEAD of FIG. 3 taken along the lineA-A of FIG. 3.

FIG. 4 is a perspective view of the IEAD housing, including afeed-through pin, before the electronic components are placed therein,and before being sealed with a cover plate.

FIG. 4A is a side view of the IEAD housing of FIG. 4.

FIG. 5 is a plan view of the empty IEAD housing shown in FIG. 4.

FIG. 5A depicts a sectional view of the IEAD housing of FIG. 5 takenalong the section line A-A of FIG. 5.

FIG. 5B shows an enlarged view or detail of the portion of FIG. 5A thatis encircled with the line B.

FIG. 6 is a perspective view of an electronic assembly, including abattery, that is adapted to fit inside of the empty housing of FIG. 4and FIG. 5.

FIGS. 6A and 6B show a plan view and side view, respectively, of theelectronic assembly shown in FIG. 6.

FIG. 7 is an exploded view of the IEAD assembly, illustrating itsconstituent parts.

FIG. 7A schematically illustrates a few alternative electrodeconfigurations that may be used with the invention.

FIG. 8A illustrates a functional block diagram of the electroniccircuits used within an IEAD of the type described herein.

FIG. 8B shows a basic boost converter circuit configuration, and is usedto model how the impedance of the battery R_(BAT) can affect itsperformance.

FIG. 9A illustrates a typical voltage and current waveform for thecircuit of FIG. 8 when the battery impedance R_(BAT) is small.

FIG. 9B shows the voltage and current waveform for the circuit of FIG.8B when the battery impedance R_(BAT) is large.

FIG. 10 shows one preferred boost converter circuit and a functionalpulse generation circuit configuration for use within the IEAD.

FIG. 11 shows an alternate boost converter circuit configuration and afunctional pulse generation circuit for use within the IEAD.

FIG. 12 shows a refinement of the circuit configuration of FIG. 11.

FIG. 13A shows one preferred schematic configuration for an implantableelectroacupunture device (IEAD) that utilizes the boost converterconfiguration shown in FIG. 10.

FIG. 13B shows current and voltage waveforms associated with theoperation of the circuit shown in FIG. 13A.

FIG. 14 shows another preferred schematic configuration for an IEADsimilar to that shown in FIG. 13A, but which uses an alternate outputcircuitry configuration for generating the stimulus pulses.

FIG. 15A shows a timing waveform diagram of representative EAstimulation pulses generated by the IEAD device during a stimulationsession.

FIG. 15B shows a timing waveform diagram of multiple stimulationsessions, and illustrates the waveforms on a more condensed time scale.

FIG. 16 shows a state diagram that shows the various states in which theIEAD may be placed through the use of an external magnet.

FIG. 17A illustrates one technique for implanting an IEAD under the skinin a location where a front surface of the IEAD faces inward toward abone surface of the patient.

FIG. 17B depicts an alternative technique for implanting an IEAD in apocket formed in a bone below a desired acupoint, with a front surfaceof the IEAD facing outward towards the skin.

Appendix A, found in Applicant's previously-filed patent applicationSer. No. 13/630,522, filed Sep. 28, 2012 (hereafter Applicant's “ParentApplication”), incorporated herein by reference, illustrates someexamples of alternate symmetrical electrode configurations that may beused with an IEAD of the type described herein.

Appendix B, also found in Applicant's Parent Application, illustrates afew examples of non-symmetrical electrode configurations that may beused with an IEAD made in accordance with the teachings herein.

Appendix C, likewise found in Applicant's Parent Application, shows anexample of the code used in the micro-controller IC (e.g., U2 in FIG.14) to control the basic operation and programming of the IEAD, e.g., toTurn the IEAD ON/OFF, adjust the amplitude of the stimulus pulse, andthe like, using only an external magnet as an external communicationelement.

Appendix D, found in Applicant's Parent Application, contains selectedpages from the WHO Standard Acupuncture Point Locations 2008 referencebook, referred to in paragraph [0023].

Appendix E, found in Applicant's Parent Application, containsillustrations of alternate case shapes that may be used with an IEAD ofthe type described herein.

Appendices A, B, C, D and E are incorporated by reference herein.

Throughout the drawings and appendices, identical reference numbersdesignate similar, but not necessarily identical, elements.

DETAILED DESCRIPTION Overview

Disclosed and claimed herein is an implantable, self-contained, leadlesselectroacupuncture (EA) device having at least two electrode contacts(also referred to as “electrodes”) mounted on the surface of itshousing. In some embodiments, these electrodes may be grouped togetherto form an electrode array. The EA device disclosed herein is adapted totreat Parkinson's disease or Essential Tremor in a patient. In onepreferred embodiment, the electrodes on the surface of the EA deviceinclude a central cathode electrode on one side of the housing, and anannular anode electrode that surrounds the cathode. In another preferredembodiment, the anode annular electrode is a ring electrode placedaround the perimeter edge of a coin-shaped housing.

A preferred application for an EA device made in accordance with theteachings presented herein is to treat Parkinson's disease or EssentialTremor. Thus, the description that follows describes in much more detailan EA device that is especially suited to be used to treat Parkinson'sdisease or Essential Tremor. However, it is to be understood that theinvention is not limited to treating only Parkinson's disease orEssential Tremor.

DEFINITIONS

As used herein, “annular”, “circumferential”, “circumscribing”,“surrounding” or similar terms used to describe an electrode orelectrode array, or electrodes or electrode arrays, (where the phrase“electrode or electrode array,” or “electrodes or electrode arrays,” isalso referred to herein as “electrode/array,” or “electrodes/arrays,”respectively) refers to an electrode/array shape or configuration thatsurrounds or encompasses a point or object, such as another electrode,without limiting the shape of the electrode/array or electrodes/arraysto be circular or round. In other words, an “annular” electrode/array(or a “circumferential” electrode/array, or a “circumscribing”electrode/array, or a “surrounding” electrode/array), as used herein,may be many shapes, such as oval, polygonal, starry, wavy, and the like,including round or circular.

“Nominal” or “about” when used with a mechanical dimension, e.g., anominal diameter of 23 mm, means that there is a tolerance associatedwith that dimension of no more than plus or minus (+/−) 5%. Thus, adimension that is nominally 23 mm means a dimension of 23 mm+/−1.15 mm(0.05×23 mm=1.15 mm).

“Nominal” when used to specify a battery voltage is the voltage by whichthe battery is specified and sold. It is the voltage you expect to getfrom the battery under typical conditions, and it is based on thebattery cell's chemistry. Most fresh batteries will produce a voltageslightly more than their nominal voltage. For example, a new nominal 3volt lithium coin-sized battery will measure more than 3.0 volts, e.g.,up to 3.6 volts under the right conditions. Since temperature affectschemical reactions, a fresh warm battery will have a greater maximumvoltage than a cold one. For example, as used herein, a “nominal 3 volt”battery voltage is a voltage that may be as high as 3.6 volts when thebattery is brand new, but is typically between 2.7 volts and 3.4 volts,depending upon the load applied to the battery (i.e., how much currentis being drawn from the battery) when the measurement is made and howlong the battery has been in use.

As explained in more detail below, a feature of the invention recognizesthat an electroacupunture modulation scheme need not be continuous,thereby allowing the implanted EA device to use a small, high density,power source to provide such non-continuous EA modulation. (Here, itshould be noted that “EA modulation,” as that phrase is used herein, isthe application of electrical stimulation pulses, at low intensities,low frequencies and low duty cycles, to at least one of the targetstimulation sites, e.g., an acupuncture site that has been identified asaffecting a particular condition, e.g., Parkinson's disease and/orEssential Tremor.) As a result, the EA device can be very small. And,because the electrodes form an integral part of the housing of the EAdevice, the EA device may thus be implanted directly at (or very nearto) the desired target tissue location, e.g., the target stimulationsite, such as the target acupoint.

In summary, and as explained more fully below in conjunction with thedescription of the treatment method for treating Parkinson's and/orEssential Tremor, the basic approach of EA stimulation includes: (1)identify an acupoint(s) or other target stimulation site that may beused to treat or mediate the particular illness, condition or deficiencythat has manifest itself in the patient, e.g., Parkinson's diseaseand/or Essential Tremor; (2) implant an EA device, made as describedherein, so that its electrodes are located to be near or on theidentified acupoint(s) or other target stimulation site; (3) apply EAmodulation, having a low intensity, low frequency, and low duty cyclethrough the electrode(s) of the EA device so that electrical stimulationpulses flow through the tissue at the target stimulation site followinga prescribed stimulation regimen over several weeks or months or years.At any time during this EA stimulation regimen, the patient's illness,condition or deficiency may be evaluated and, as necessary, theparameters of the EA modulation applied during the EA stimulationregimen may be adjusted or “tweaked” in order to improve the resultsobtained from the EA modulation.

Conditions Treated

Parkinson's disease (PD) is a common disorder that affects the brain'sability to control movement. Parkinson's progressively worsens overtime, although the rate of worsening condition varies greatly fromperson to person. Many people with the disease who are treated may beable to live years without serious disability. A number of treatmentsare available to help manage the symptoms and improve a person's qualityof life. However, there is no cure for the disease at this time.

The severity of Parkinson's is generally measured by the UnifiedParkinson's Disease Rating Scale (UPDRS). The UPDRS has four categories:(I) Mentation, Behavior and Mood; (II) Activities of Daily Living; (III)Motor Examination; (4) Complications of Therapy. The third category,motor, was created largely from the Webster Scale, which was previouslythe most commonly used scale. The higher the score, the more severe theParkinson's.

Many complications arise from drugs, such as dyskinesia and dystonia.Thus, the current scale attempts to account for the affect on thepatient of using drugs for treatment. Furthermore, drugs become lesseffective over time in Parkinson's patients.

The Modified Hoehn and Yahr Staging Scale categorizes a patient'sdisease state in terms of stages, ranging from zero to 5. Stage zeromeans there are no signs of the disease. Stage 1 means there isunilateral disease. Stage 1.5 means there is unilateral plus axialinvolvement. Stage 2 means there is bilateral disease, withoutimpairment of balance. Stage 2.5 means there is mild bilateral disease,with recovery on pull test. Stage 3 means there is mild to moderatebilateral disease, some postural instability and physical independence.Stage 4 means there is severe disability, but the patient is still ableto walk or stand unassisted. The final stage, stage 5, means that thepatient is wheelchair bound or bedridden unless aided.

Essential tremor is a disorder of the nervous system that causes arhythmic shaking or tremor. It can affect almost any part of the bodybut the trembling most often occurs in the hands and is especiallybothersome during the attempt to do simple tasks like drinking from aglass or writing with a pencil. Essential tremor may also affect one'shead, voice, arms, or legs. While it is not the same as Parkinson'sdisease, the tremor of Parkinson's disease resembles essential tremorand some of the same treatments, e.g., deep brain stimulation, are givento both disorders.

In three clinical studies authored by mostly the same group of authors,there were two acupoints in common—LR3 and GB34—and the successfullowering of the average patient UPDRS score was achieved by somesignificant measure. See, Jung, J C, Kim K H, Park Y C, et al. [Thestudy on the effect of acupuncture on UPDRS and heart rate variabilityin the patients with idiopathic Parkinson's disease]. J Korean AcupunctMoxibust Soc 2006; 23: 143-153 (in Korean with English translation)(hereafter, “Jung 2006”); Park Y C, Chang D I, Lee Y H, Park D S. [Thestudy on the effect of acupuncture treatment in patients with idiopathicParkinson's disease]. J Korean Acupunct Moxibust Soc 2007; 24: 43-54 (inKorean with English translation) (hereafter, “Park 2007”); Kang M K, LeeS H, Hong J M, Park S M, Kang J W, Park H J, Lim S, Chang D I, Lee Y H.[Effect of Electroacupuncture on Patients with Idiopathic Parkinson'sDisease]. J Korean Acupunct Moxibust Soc 2004; 21; 5:59-68 (in Korean)(hereafter, “Kang 2004”).

In addition, that main group of authors showed in experimentalParkinson's rats that manual acupuncture at GB34 and LR3 significantlyimproved the motor deficit. See, Park, H. J., Um, S., Joo, W. S., Yin,C. S., Lee, H. S., Lee, H. J., . . . & Chung, J. H. (2003). Acupunctureprevents 6-hydroxydopamine-induced neuronal death in the nigrostriataldopaminergic system in the rat Parkinson's disease model. Experimentalneurology, 180(1), 93-98 (Park 2003”).

In two of the three aforementioned studies, manual acupuncture wasperformed at acupoints GB34 and at LR3 (and at ST36 in one of thestudies). In the third study, electroacupuncture was performed at GB34and LR3. Over a course of four weeks, with acupuncture or EA for fifteenminute sessions twice a week, patients saw about eight to thirty percentreductions in their baseline UPDRS score. See, Jung 2006, Park 2007,Kang 2004. Applicant believes greater reductions can be brought aboutover longer stimulation sessions (i.e., 30 minute sessions) and overtime.

For a study utilizing both body and scalp acupoints including GB34 withsuccess, see, Chang, X. H., Zhang, L. Z., & Li, Y. J. (2008).Observation on therapeutic effect of acupuncture combined with medicineon Parkinson disease]. Zhongguo zhen jiu=Chinese acupuncture &moxibustion, 28(9), 645 (hereafter, “Chang 2008”).

While the mechanism of action is not known, there are a number oftheories that give credence to the efficacious results seen in certainacupuncture studies. The mechanism of action in stimulation at GB34 islikely to involve the following areas of the brain: the putamen and theprimary motor cortex. In an MRI study utilizing three groups—an overplacebo (or control) group, a verum acupuncture group, and a coverplacebo group (nonpenetrating needle group)—the putamen and primarymotor cortex were activated when patients with Parkinson's diseasereceived acupuncture treatment at acupoint GB34 and the activations werecorrelated with improved motor function. See, Chae, Y., Lee, H., Kim,H., Kim, C. H., Chang, D. I., Kim, K. M., & Park, H. J. (2009). Parsingbrain activity associated with acupuncture treatment in Parkinson'sdiseases, Movement Disorders, 24(12), 1794-1802 (hereafter, “Chae2009”). In addition, expectations towards acupuncture modality elicitedactivation over the anterior cingulated gyrus, the superior frontalgyrus, and the superior temporal gyrus. The comparison of the covertplacebo group to the overt placebo group allowed this deduction. See,Chae 2009.

In another MRI study of the brain during acupuncture at GB34, in healthypeople, showed that electroacupuncture stimulation at the left GB34specifically activated the right putamen, caudate body, claustrum,thalamus, cerebellum, as well as the left caudate body, ventral lateralthalamus, and cerebellum—all of which are related to motor function.See, Na, B. J., Jahng, G. H., Park, S. U., Jung, W. S., Moon, S. K.,Park, J. M., & Bae, H. S. (2009). An fMRI study of neuronal specificityof an acupoint: electroacupuncture stimulation of Yanglingquan (GB34)and its sham point. Neuroscience letters, 464(1), 1-5 (hereafter, “Na2009”). Electroacupuncture at the sham point, on the other hand,specifically activated the right BA6, BA8, BA40, BA44, thalamus, as wellas the left thalamus and cerebellum. See, Nah 2009. Electroacupunctureat GB34 and its sham point induced specific neuronal responses—and EA atGB34 appears to be more related to motor function than EA at its shampoint, even though the sham point is located very closeby, suggestive ofacupoint specificity.

The mechanism of action may involve the inhibition of the motor system.In a study on healthy people, acupuncture at GB34 was compared to shamacupuncture using a nonpenetrating needle. See, Zunhammer, M.,Eichhammer, P., Franz, J., Hajak, G., & Busch, V. (2012). Effects ofacupuncture needle penetration on motor system excitability.Neurophysiologie Clinique/Clinical Neurophysiology (hereafter,“Zunhammer 2012”). Verum acupuncture compared to sham acupuncturesignificantly increased resting motor threshold. Thus, it may be thatacupuncture at GB34 is reducing the excitability of the motor system inParkinson's patients.

In another study on healthy people, acupuncture at GB34 and a controlgroup who rested demonstrated that acupuncture at GB34 is effective fordecreasing muscle fatigue (during an arm flexion test). See, KwonHoyoung, Kim Jeonghwan (2008). The effects of Yanggnungch'on (G34)acupuncture on the muscle. Journal of Meridian & Acupoint Society:Society of Meridian & Acupoint; 25(2): 115-123. Korean with Englishabstract (hereafter, “Kwon 2008”).

The mechanism of action may involve the regulation of dopamine contentin the striatum. In a study of experimental hemi-parkinsonism ratsbefore and after EA at LR3, SP6, ST36, and GB34 on the lesioned side, EAtreatment could elevate the dopamine level of the lesioned side striatumand prevent D₂ receptor up-regulation. See, Lin, Y., & Lin, X. (2000).Comparative study of D2 receptors and dopamine content in striatumbefore and after electro-acupuncture treatment in rats. Chinese medicaljournal, 113(5), 408 (hereafter, “Lin 2000”).

For an example of the enhanced survival of dopaminergic neurons in theexperimental rat Parkinson's brain after acupuncture (at two limbacupoints in Park's study and at one scalp and one back acupoint inLian's study), see, Park 2003, Liang 2002. See also, Liu, X. Y., Zhou,H. F., Pan, Y. L., Liang, X. B., Mu, D. B., Xue, B., . . . & Wang, X. M.(2004). Electro-acupuncture stimulation protects dopaminergic neuronsfrom inflammation-mediated damage in medial forebrain bundle-transectedrats. Experimental neurology, 189(1), 189-196 (hereafter, “Liu 2004”).

Last, the mechanism of action for acupuncture stimulation of scalpacupoints (specifically at GV20 and a single back acupoint GV14) maystem from the collaboration of its anti-inflammatory and neurotrophicactions. The neuroprotective effect of high frequency stimulation inexperimental Parkinson's rats (or “medial forebrain bundle-transectedrats”) has been demonstrated in two studies conducted by Han for which asingle scalp acupoint and a single back acupoint are utilized alone.See, Liang 2002, Liu 2004.

Locations Stimulated and Stimulation Paradigms/Regimens

The acupoints for stimulation for purposes of this application are atleast one acupoint located in a limb of the patient, and one acupointlocated in the scalp. The limb acupoint is GB34. The acupoint GB34,which might be referred to as “Yanglingquan” or its different spellings(e.g., “Yanglingchuan”), is located on the leg in the fossa anterior andinferior to the head of the fibula. See FIG. 1D. See also, WHO StandardAcupuncture Point Locations 2008, page 188, incorporated herein byreference.

For purposes of this patent application, the scalp stimulation locationhas been identified as acupoint GV20. Its location is shown in FIGS. 1A,1B and 1C. The acupoint GV20 is also sometimes referred to as Baihui,and may also be designated as either DU20 or GV20. Both “GV” and “DU”stand for the Governing Vessel meridian. GV20 is located on the head atthe midpoint of the connecting line between the auricular apices. It isalso about 4.5 inches superior to the anterior hairline on the anteriormedian line. See also, WHO Standard Acupuncture Point Locations 2008,page 213, incorporated herein by reference.

For stimulation at either the limb (GB34) or at the scalp (GV20), thestimulation parameters are the same.

The stimulation duration should be between fifteen minutes and sixtyminutes, and, the rate of stimulation occurrence should be between oncedaily and once every other week. While the acupuncture studies on whichApplicant relies for the utilization of the limb acupoint GB34 applyacupuncture with a short duration of fifteen minutes, see, Kang 2004,Park 2007, Jung 2006, Applicant believes the history and experience ofacupuncture science support a longer stimulation duration.

The electrical parameters of stimulation should require a frequencybetween 1 Hz and 15 Hz for a low frequency setting, and between 100 Hzand 120 Hz for a high frequency setting. Thus, there are two differentsettings for the frequency: a high and a low frequency setting. Theamplitude of the stimulus pulses should be between 1 mA and 15 mA, andthe pulse width of the stimulation pulses should be about 0.5 ms.

For an example of successful scalp electroacupuncture stimulationutilizing low frequency, see e.g., Shun 2003. For an example ofsuccessful high frequency scalp electroacupuncture stimulation or highfrequency limb electroacupuncture stimulation, respectively, see e.g.,Yong 2009, Liang 2002, Liu 2004; and Kang 2004. Manual acupuncture atthe identified limb point also brings about positive results inParkinson's. See e.g., Park 2007, Jung 2006.

In a study performed by Yong et al, patients with high baseline UPDRSmotor scores saw reductions of about 24%. See, Yong 2009. Thestimulation parameters, however, were not manual acupuncture like mostsuccessful acupuncture studies known to Applicant for treatment ofParkinson's disease or Essential Tremor, but high frequencyelectroacupuncture. The stimulation parameters were 100 Hz, 2-4 mA, withcontinuous wave, 30 minutes daily for six days a week over a course offive weeks. However, EA was performed only at one or two of the fivestimulated acupoints depending upon the symptoms.

In a study performed by J S Han, who is well known for his work in pain,high frequency EA was utilized in rats and improvement in lesions weremeasured. In a partially lesioned rat model of Parkinson's disease, highfrequency stimulation brought about a stop in the degeneration ofdopaminergic neurons in the substantia nigra and upregulating the levelsof brain-derived neurotrophic factor (BDNF) mRNA in the subfields of theventral midbrain. In this rat study, low frequency stimulation did notsimilarly affect the brain. See, Liang, X. B., Liu, X. Y., Li, F. Q.,Luo, Y., Lu, J., Zhang, W. M., . . . & Han, J. S. (2002). Long-termhigh-frequency electro-acupuncture stimulation prevents neuronaldegeneration and up-regulates BNF mRNA in the substantia nigra andventral tegmental area following medial forebrain bundle axotomy.Molecular brain research, 108(1), 51-50 (hereafter, “Liang 2002”).

The pulse width Applicant has selected to use is between 0.5 ms and 2 msin consideration of Applicant's understanding of neuromodulation and therecruitment of fibers and in consideration of at least one study forwhich a long pulse width of 2 ms was utilized. See, Shun 2003.

The rate of occurrence of the stimulation sessions should be asfrequently as daily and as infrequent as once weekly. For examples ofimprovement of Parkinson's symptoms from acupuncture stimulation appliedat acupoints GV20 or GB34 administered twice weekly, see, Kang 2004,Park 2007, Jung 2006. For an example of more frequent or dailystimulation and success, see, Wang, S., Cai, Y. Y., Shang, Y. J., &Jin-Dong, L. (2006). Effects of head point-through-pointelectroacupuncture on SOD and LPO in the patient of Parkinson's disease.Zhongguo Zhen Jiu, 26(4), 240-242 (hereafter, “Wang 2006”); Chang 2008.

Specific Example

A specific example of the invention will next be described incombination with a more detailed explanation of the figures. Althoughone specific example is being described, there are many variations of itthat are generally referred to in the description of the specificexample as “embodiments”.

The EA device of this specific example being described comprises animplantable, coin-shaped, self-contained, symmetrical, leadlesselectroacupuncture (EA) device having at least two electrode contactsmounted on the surface of its housing. In one preferred embodiment, theelectrodes include a central cathode electrode on a front side of thehousing, and an annular anode electrode that surrounds the cathode. Inanother preferred embodiment, the anode annular electrode is a ringelectrode placed around the perimeter edge of the coin-shaped housing.

The EA device is leadless. This means there are no leads or electrodesat the distal end of leads (common with most implantable electricalstimulators) that have to be positioned and anchored at a desiredstimulation site. Also, because there are no leads, no tunneling throughbody tissue is required in order to provide a path for the leads toreturn and be connected to a tissue stimulator (also common with mostelectrical stimulators).

The EA device is adapted to be implanted through a very small incision,e.g., less than 2-3 cm in length, directly adjacent to a selectedacupuncture site (“acupoint”) known to moderate or affect body weight,fat or lipid profile.

The EA device is relatively easy to implant. Also, most embodiments aresymmetrical. This means that there is no way that it can be implantedincorrectly. The basic implant procedure involves cutting an incision,forming an implant pocket, and sliding the device in place through theincision. Only minor, local anesthesia need be used. No major orsignificant complications are envisioned for the implant procedure. TheEA device can also be easily and quickly explanted, if needed.

The EA device is self-contained. It includes a primary battery toprovide its operating power. It includes all of the circuitry it needs,in addition to the battery, to allow it to perform its intended functionfor several years. Once implanted, the patient will not even know it isthere, except for a slight tingling that may be felt when the device isdelivering stimulus pulses during a stimulation session. Also, onceimplanted, the patient can just forget about it. There are nocomplicated user instructions that must be followed. Just turn it on. Nomaintenance is needed. Moreover, should the patient want to disable theEA device, i.e., turn it OFF, or change stimulus intensity, he or shecan easily do so using, e.g., an external magnet.

The EA device can operate for several years because it is designed to bevery efficient. Stimulation pulses applied by the EA device at aselected acupoint through its electrodes formed on its case are appliedat a very low duty cycle in accordance with a specified stimulationregimen. The stimulation regimen applies EA stimulation during astimulation session that lasts at least 10 minutes, typically 30minutes, and rarely longer than 70 minutes. These stimulation sessions,however, occur at a very low duty cycle. In one preferred treatmentregimen, for example, a stimulation session having a duration of 60minutes is applied to the patient just once every seven days. Thestimulation regimen, and the selected acupoint at which the stimulationis applied, are designed and selected to provide efficient and effectiveEA stimulation for the treatment of Parkinson's disease or EssentialTremor.

The EA device is, compared to most implantable medical devices,relatively easy to manufacture and uses few components. This not onlyenhances the reliability of the device, but helps keep the manufacturingcosts low, which in turn allows the device to be more affordable to thepatient. One key feature included in the mechanical design of the EAdevice is the use of a radial feed-through assembly to connect theelectrical circuitry inside of its housing to one of the electrodes onthe outside of the housing. The design of this radial feed-through pinassembly greatly simplifies the manufacturing process. The processplaces the temperature sensitive hermetic bonds used in the assembly—thebond between a pin and an insulator and the bond between the insulatorand the case wall—away from the perimeter of the housing as the housingis hermetically sealed at the perimeter with a high temperature laserwelding process, thus preserving the integrity of the hermetic bondsthat are part of the feed-through assembly.

In operation, the EA device is safe to use. There are no horrificfailure modes that could occur. Because it operates at a very low dutycycle (i.e., it is OFF much, much more than it is ON), it generateslittle heat. Even when ON, the amount of heat it generates is not much,less than 1 mW, and is readily dissipated. Should a component or circuitinside of the EA device fail, the device will simply stop working. Ifneeded, the EA device can then be easily explanted.

Another key feature included in the design of the EA device is the useof a commercially-available battery as its primary power source. Small,thin, disc-shaped batteries, also known as “coin cells,” are quitecommon and readily available for use with most modern electronicdevices. Such batteries come in many sizes, and use variousconfigurations and materials. However, insofar as applicants are aware,such batteries have never been used in implantable medical devicespreviously. This is because their internal impedance is, or has alwaysthought to have been, much too high for such batteries to be ofpractical use within an implantable medical device where powerconsumption must be carefully monitored and managed so that the device'sbattery will last as long as possible, and so that dips in the batteryoutput voltage (caused by any sudden surge in instantaneous batterycurrent) do not occur that could compromise the performance of thedevice. Furthermore, the energy requirements of other active implantabletherapies are far greater than can be provided by such coin cellswithout frequent replacement.

The EA device of this specific example advantageously employspower-monitoring and power-managing circuits that prevent any suddensurges in battery instantaneous current, or the resulting drops inbattery output voltage, from ever occurring, thereby allowing a wholefamily of commercially-available, very thin, high-output-impedance,relatively low capacity, small disc batteries (or “coin cells”) to beused as the EA device's primary battery without compromising the EAdevice's performance. As a result, instead of specifying that the EAdevice's battery must have a high capacity, e.g., greater than 200 mAh,with an internal impedance of, e.g., less than 5 ohms, which wouldeither require a thicker battery and/or preclude the use ofcommercially-available coin-cell batteries, the EA device of the presentinvention can readily employ a battery having a relatively low capacity,e.g., less than 60 mAh, and a high battery impedance, e.g., greater than5 ohms.

Moreover, the power-monitoring, power-managing, as well as the pulsegeneration, and control circuits used within the EA device arerelatively simple in design, and may be readily fashioned fromcommercially-available integrated circuits (IC's) orapplication-specific integrated circuits (ASIC's), supplemented withdiscrete components, as needed. In other words, the electronic circuitsemployed within the EA device need not be complex nor expensive, but aresimple and inexpensive, thereby making it easier to manufacture the EAdevice and to provide it to patients at an affordable cost.

Mechanical Design

Turing first to FIG. 1, there is shown a perspective view of onepreferred embodiment of an implantable electroacupuncture device (IEAD)100 that may be used to treat Parkinson's disease and/or EssentialTremor in accordance with the teachings disclosed herein. The IEAD 100may also sometimes be referred to as an implantable electroacupuncturestimulator (IEAS). As seen in FIG. 1, the IEAD 100 has the appearance ofa disc or coin, having a front side 102, a back side 106 (not visible inFIG. 1) and an edge side 104.

As used herein, the “front” side of the IEAD 100 is the side that ispositioned so as to face the target stimulation point (e.g., the desiredacupoint) where EA is to be applied when the IEAD is implanted. The“back” side is the side opposite the front side and is the farthest awayfrom the target stimulation point when the IEAD is implanted. The “edge”of the IEAD is the side that connects or joins the front side to theback side. In FIG. 1, the IEAD 100 is oriented to show the front side102 and a portion of the edge side 104.

Many of the features associated with the mechanical design of the IEAD100 shown in FIG. 1 are the subject of a prior U.S. Provisional PatentApplication, entitled “Radial Feed-Through Packaging for An ImplantableElectroacupuncture Device”, Application No. 61/676,275, filed 26 Jul.2012, which application is incorporated here by reference.

It should be noted here that throughout this application, the terms IEAD100, IEAD housing 100, bottom case 124, can 124, or IEAD case 124, orsimilar terms, are used to describe the housing structure of the EAdevice. In some instances it may appear these terms are usedinterchangeably. However, the context should dictate what is meant bythese terms. As the drawings illustrate, particularly FIG. 7, there is abottom case 124 that comprises the “can” or “container” wherein thecomponents of the IEAD 100 are first placed and assembled duringmanufacture of the IEAD 100. When all of the components are assembledand placed within the bottom case 124, a cover plate 122 is welded tothe bottom case 124 to form the hermetically-sealed housing of the IEAD.The cathode electrode 110 is attached to the outside of the bottom case124 (which is the front side 102 of the device), and the ring anodeelectrode 120 is attached, along with its insulating layer 129, aroundthe perimeter edge 104 of the bottom case 124. Finally, a layer ofsilicone molding 125 covers the IEAD housing except for the outsidesurfaces of the anode ring electrode and the cathode electrode.

The embodiment of the IEAD 100 shown in FIG. 1 utilizes two electrodes,a cathode electrode 110 that is centrally positioned on the front side102 of the IEAD 100, and an anode electrode 120. The anode electrode 120is a ring electrode that fits around the perimeter edge 104 of the IEAD100. Not visible in FIG. 1, but which is described hereinafter inconnection with the description of FIG. 7, is a layer of insulatingmaterial 129 that electrically insulates the anode ring electrode 120from the perimeter edge 104 of the housing or case 124.

Not visible in FIG. 1, but a key feature of the mechanical design of theIEAD 100, is the manner in which an electrical connection is establishedbetween the ring electrode 120 and electronic circuitry carried insideof the IEAD 100. This electrical connection is established using aradial feed-through pin that fits within a recess formed in a segment ofthe edge of the case 124, as explained more fully below in connectionwith the description of FIGS. 5, 5A, 5B and 7.

In contrast to the feed-through pin that establishes electrical contactwith the anode electrode, electrical connection with the cathodeelectrode 110 is established simply by forming or attaching the cathodeelectrode 110 to the front surface 102 of the IEAD case 124. In order toprevent the entire case 124 from functioning as the cathode (which isdone to better control the electric fields established between the anodeand cathode electrodes), the entire IEAD housing is covered in a layerof silicone molding 125 (see FIG. 7), except for the outside surface ofthe anode ring electrode 120 and the cathode electrode 110.

The advantage of using a central cathode electrode and a ring anodeelectrode is described in U.S. Provisional Patent Application No.61/672,257, filed 6 Mar. 2012, entitled “Electrode Configuration forImplantable Electroacupuncture Device”, which application isincorporated herein by reference. One significant advantage of thiselectrode configuration is that it is symmetrical. That is, whenimplanted, the surgeon or other medical personnel performing the implantprocedure, need only assure that the cathode side of the IEAD 100, which(for the embodiment shown in FIGS. 1-7) is the front side of the device,facing the target tissue location that is to be stimulated.

In this regard, it should be noted that while the target stimulationpoint is generally identified by an “acupoint,” which is typically shownin drawings and diagrams as residing on the surface of the skin, thesurface of the skin is not the actual target stimulation point. Rather,whether such stimulation comprises manual manipulation of a needleinserted through the skin at the location on the skin surface identifiedas an “acupoint”, or whether such stimulation comprises electricalstimulation applied through an electrical field oriented to causestimulation current to flow through the tissue at a prescribed depthbelow the acupoint location on the skin surface, the actual targettissue point to be stimulated is located beneath the skin at a depththat varies depending on the particular acupoint location. Whenstimulation is applied at the target tissue point, such stimulation iseffective at treating a selected condition of the patient, e.g.,Parkinson's disease, because there is something in the tissue at thatlocation, or near that location, such as a nerve, a tendon, a muscle, orother type of tissue, that responds to the applied stimulation in amanner that contributes favorably to the treatment of the conditionexperienced by the patient.

For purposes of the present application, some of the target acupointsare located near a bone of the patient. When the bone is very close tothe skin surface, the location of the bone may prevent deep tissuestimulation, and may even prevent or hamper implantation at a desireddepth. This condition—of having a bone near the skin surface—isillustrated schematically in FIGS. 17A and 17B. As seen in thesefigures, the bone is shown generally as being right under the skin 80,with not much tissue separating the two. These two figures assume thatthe actual desired target stimulation point is below acupoint 90 at anerve 87 (or some other tissue formation) between the underneath side ofthe skin 80 and the top surface of the bone 89. Hence, the challenge isto implant the IEAD 100 in a manner that provides effective EAstimulation at the desired target stimulation site, e.g., at the nerve87 (or other target tissue formation) that resides beneath the acupoint90. FIGS. 17A and 17B illustrate alternative methods for achieving thisgoal.

Shown in FIG. 17A is one alternative for implanting the IEAD 100 at anacupoint 90 located on the surface of the skin 80 above a bone 89, wherethe actual target stimulation point is a nerve 87, or some other tissueformation, that is located between the bone 89 and the underneath sideof the skin 80. As shown in FIG. 17A, the IEAD 100 is implanted rightunder the skin with its front surface 102 facing down towards the targettissue location 87. This allows the electric fields (illustrated by theelectric field gradient lines 88) generated by the IEAD 100 when EAstimulation pulses are to be generated to be most heavily concentratedat the target tissue stimulation site 87. These electric field gradientlines 88 are established between the two electrodes 110 and 120 of theIEAD. For the embodiment shown here, these two electrodes comprise aring electrode 120, positioned around the perimeter edge of the IEADhousing, and a central electrode 110, positioned in the center of thefront surface 102 of the IEAD housing. These gradient lines 88 are mostconcentrated right below the central electrode, which is where thetarget tissue location 87 resides. Hence, the magnitude of theelectrical stimulation current will also be most concentrated at thetarget tissue location 87, which is the desired result.

FIG. 17B shows another alternative for implanting the IEAD 100 at theacupoint 90 located on the surface of the skin 80 above the bone 89,where the actual target stimulation point is a nerve 87, or some othertissue formation, that is located between the bone 89 and the underneathside of the skin 80. As shown in FIG. 17B, the IEAD 100 is implanted ina pocket 81 formed in the bone 89 at a location underneath the acupoint90. In this instance, and as the elements are oriented in FIG. 17B, thefront surface 102 of the IEAD 100 faces upwards towards the targettissue location 87. As with the implant configuration shown in FIG. 17A,this configuration also allows the electric fields (illustrated by theelectric field gradient lines 88) that are generated by the IEAD 100when EA stimulation pulses are generated to be most heavily concentratedat the target tissue stimulation site 87.

There are advantages and disadvantages associated with each of the twoalternative implantation configurations shown in FIGS. 17A and 17B.Generally, the implantation procedure used to achieve the configurationshown in FIG. 17A is a simpler procedure with fewer risks. That is, allthat need to be done by the surgeon to implant that EA device 100 asshown in FIG. 17A is to make an incision 82 in the skin 80 a shortdistance, e.g., 10-15 mm, away from the acupoint 90. This incisionshould be made parallel to the nerve 87 so as to minimize the risk ofcutting the nerve 87. A slot is then formed at the incision by liftingthe skin closest to the acupoint up at the incision and by carefullysliding the IEAD 100, with its front side 102 facing the bone, into theslot so that the center of the IEAD is located under the acupoint 90.Care is taken to assure that the nerve 87 resides below the frontsurface of the IEAD 100 as the IEAD is slid into position.

In contrast, if the implant configuration shown in FIG. 17B is to beused, then the implant procedure is somewhat more complicated withsomewhat more risks. That is, to achieve the implant configuration shownin FIG. 17B, a sufficiently large incision must be made in the skin atthe acupoint 90 to enable the skin 80 to be peeled or lifted away toexpose the surface of the bone so that the cavity 81 may be formed inthe bone 89. While doing this, care must be exercised to hold the nerve87 (or other sensitive tissue areas) away from the cutting tools used toform the cavity 81. Once the cavity 81 is formed, the IEAD 100 is laidin the cavity, with its front surface facing upward, the nerve 87 (andother sensitive tissue areas) are carefully repositioned above the IEAD100, and the skin is sewn or clamped to allow the incision to heal.

However, while the surgical procedure and attendant risks may be morecomplicated when the configuration of FIG. 17B is employed, the finalresults of the configuration of FIG. 17B may be more aestheticallypleasing to the patient than are achieved with the configuration of FIG.17A. That is, given the shallow space between the skin and the bone at adesired acupoint, the implant configuration of FIG. 17A will likelyresult in a small hump or bump at the implant site, whereas the implantconfiguration of FIG. 17B should not exhibit such a small hump or bump.

Insofar as Applicant is aware at the present time, of the two implantconfigurations shown in FIGS. 17A and 17B, there is no theoreticalperformance advantage that one implant configuration provides over theother. That is, both implant configurations should perform equally wellinsofar as providing EA stimulation pulses at the desired target tissuelocation 87 is concerned.

Thus, which implant configuration is used will, in large part, bedictated by individual differences in patient anatomy, patientpreference, and surgeon preferences and skill levels.

From the above, it is seen that one of the main advantages of using asymmetrical electrode configuration that includes a centrally locatedelectrode surrounded by an annular electrode, as is used in theembodiment described in connection with FIGS. 1-7, is that the preciseorientation of the IEAD 100 within its implant location is notimportant. So long as one electrode faces and is centered over (orunder) the desired target location, and the other electrode surroundsthe first electrode (e.g., as an annular electrode), a strong electricfield gradient is created that is aligned with the desired target tissuelocation. This causes the EA stimulation current to flow at (or verynear to) the target tissue location 87.

Turning next to FIG. 2, there is shown a plan view of the “front” sideof the IEAD 100. As seen in FIG. 2, the cathode electrode 110 appears asa circular electrode, centered on the front side, having a diameter D1.The IEAD housing has a diameter D2 and an overall thickness or width W2.For the preferred embodiment shown in these figures, D1 is about 4 mm,D2 is about 23 mm and W2 is a little over 2 mm (2.2 mm).

FIG. 2A shows a side view of the IEAD 100. The ring anode electrode 120,best seen in FIG. 2A, has a width W1 of about 1.0 mm, or approximately ½of the width W2 of the IEAD.

FIG. 3 shows a plan view of the “back” side of the IEAD 100. As will beevident from subsequent figure descriptions, e.g., FIGS. 5A and 5B, theback side of the IEAD 100 comprises a cover plate 122 that is welded inplace once the bottom case 124 has all of the electronic circuitry, andother components, placed inside of the housing.

FIG. 3A is a sectional view of the IEAD 100 of FIG. 1 taken along theline A-A of FIG. 3. Visible in this sectional view is the feed-throughpin 130, including the distal end of the feed-through pin 130 attachedto the ring anode electrode 120. Also visible in this section view is anelectronic assembly 133 on which various electronic components aremounted, including a disc-shaped battery 132. FIG. 3A furtherillustrates how the cover plate 122 is welded, or otherwise bonded, tothe bottom case 124 in order to form the hermetically-sealed IEADhousing 100.

FIG. 4 shows a perspective view of the IEAD case 124, including thefeed-through pin 130, before the electronic components are placedtherein, and before being sealed with the “skin side” cover plate 122.The case 124 is similar to a shallow “can” without a lid, having a shortside wall around its perimeter. Alternatively, the case 124 may beviewed as a short cylinder, closed at one end but open at the other.(Note, in the medical device industry the housing of an implanted deviceis often referred to as a “can”.) The feed-through pin 130 passesthrough a segment of the wall of the case 124 that is at the bottom of arecess 140 formed in the wall. The use of this recess 140 to hold thefeed-through pin 130 is a key feature of the invention because it keepsthe temperature-sensitive portions of the feed-through assembly (thoseportions that could be damaged by excessive heat) away from the thermalshock and residual weld stress inflicted upon the case 124 when thecover plate 122 is welded thereto.

FIG. 4A is a side view of the IEAD case 124, and shows an annular rim126 formed on both sides of the case 124. The ring anode electrode 120fits between these rims 126 once the ring electrode 120 is positionedaround the edge of the case 124. (This ring electrode 120 is, for mostconfigurations, used as an anode electrode. Hence, the ring electrode120 may sometimes be referred to herein as a ring anode electrode.However, it is noted that the ring electrode could also be employed as acathode electrode, if desired.) A silicone insulator layer 129 (see FIG.7) is placed between the backside of the ring anode electrode 120 andthe perimeter edge of the case 124 where the ring anode electrode 120 isplaced around the edge of the case 124.

FIG. 5 shows a plan view of the empty IEAD case 124 shown in theperspective view of FIG. 4. An outline of the recess cavity 140 is alsoseen in FIG. 5, as is the feed-through pin 130. A bottom edge of therecess cavity 140 is located a distance D5 radially inward from the edgeof the case 124. In one embodiment, the distance D5 is between about 2.0to 2.5 mm. The feed-through pin 130, which is just a piece of solidwire, is shown in FIG. 5 extending radially outward from the case 124above the recess cavity 140 and radially inward from the recess cavitytowards the center of the case 124. The length of this feed-through pin130 is trimmed, as needed, when a distal end (extending above therecess) is connected (welded) to the anode ring electrode 120 (passingthrough a hole in the ring electrode 120 prior to welding) and when aproximal end of the feed-through pin 130 is connected to an outputterminal of the electronic assembly 133.

FIG. 5A depicts a sectional view of the IEAD housing 124 of FIG. 5 takenalong the section line A-A of FIG. 5. FIG. 5B shows an enlarged view ordetail of the portion of FIG. 5A that is encircled with the line B.Referring to FIGS. 5A and 5B jointly, it is seen that the feed-throughpin 130 is embedded within an insulator material 136, which insulatingmaterial 136 has a diameter of D3. The feed-through pin assembly (whichpin assembly comprises the combination of the pin 130 embedded into theinsulator material 136) resides on a shoulder around an opening or holeformed in the bottom of the recess 140 having a diameter D4. For theembodiment shown in FIGS. 5A and 5B, the diameter D3 is 0.95-0.07 mm,where the −0.07 mm is a tolerance. (Thus, with the tolerance considered,the diameter D3 may range from 0.88 mm to 0.95 mm) The diameter D4 is0.80 mm with a tolerance of −0.06 mm. (Thus, with the toleranceconsidered, the diameter D4 could range from 0.74 mm to 0.80 mm).

The feed-through pin 130 is preferably made of pure platinum 99.95%. Apreferred material for the insulator material 136 is Ruby or alumina.The IEAD case 124, and the cover 122, are preferably made from titanium.The feed-through assembly, including the feed-through pin 130,ruby/alumina insulator 136 and the case 124 are hermetically sealed as aunit by gold brazing. Alternatively, active metal brazing can be used.(Active metal brazing is a form of brazing which allows metal to bejoined to ceramic without metallization.)

The hermeticity of the sealed IEAD housing is tested using a helium leaktest, as is common in the medical device industry. The helium leak rateshould not exceed 1×10⁻⁹ STD cc/sec at 1 atm pressure. Other tests areperformed to verify the case-to-pin resistance (which should be at least15×10⁶ Ohms at 100 volts DC), the avoidance of dielectric breakdown orflashover between the pin and the case 124 at 400 volts AC RMS at 60 Hzand thermal shock.

One important advantage provided by the feed-through assembly shown inFIGS. 4A, 5, 5A and 5B is that the feed-through assembly made from thefeed-through pin 130, the ruby insulator 136 and the recess cavity 140(formed in the case material 124) may be fabricated and assembled beforeany other components of the IEAD 100 are placed inside of the IEAD case124. This advantage greatly facilitates the manufacture of the IEADdevice.

Turning next to FIG. 6, there is shown a perspective view of anelectronic assembly 133. The electronic assembly 133 includes amulti-layer printed circuit (pc) board 138, or equivalent mountingstructure, on which a battery 132 and various electronic components 134are mounted. This assembly is adapted to fit inside of the empty bottomhousing 124 of FIG. 4 and FIG. 5.

FIGS. 6A and 6B show a plan view and side view, respectively, of theelectronic assembly 133 shown in FIG. 6. The electronic components areassembled and connected together so as to perform the circuit functionsneeded for the IEAD 100 to perform its intended functions. These circuitfunctions are explained in more detail below under the sub-heading“Electrical Design”. Additional details associated with these functionsmay also be found in many of the patent applications referenced above inParagraph [0001].

FIG. 7 shows an exploded view of the complete IEAD 100, illustrating itsmain constituent parts. As seen in FIG. 7, the IEAD 100 includes,starting on the right and going left, a cathode electrode 110, a ringanode electrode 120, an insulating layer 129, the bottom case 124 (the“can” portion of the IEAD housing, and which includes the feed-throughpin 130 which passes through an opening in the bottom of the recess 140formed as part of the case, but wherein the feed-through pin 130 isinsulated and does not make electrical contact with the metal case 124by the ruby insulator 136), the electronic assembly 133 (which includesthe battery 132 and various electronic components 134 mounted on a pcboard 138) and the cover plate 122. The cover plate 122 is welded to theedge of the bottom case 124 using laser beam welding, or some equivalentprocess, as one of the final steps in the assembly process.

Other components included in the IEAD assembly, but not necessarilyshown or identified in FIG. 7, include adhesive patches for bonding thebattery 132 to the pc board 138 of the electronic assembly 133, and forbonding the electronic assembly 133 to the inside of the bottom of thecase 124. To prevent high temperature exposure of the battery 132 duringthe assembly process, conductive epoxy is used to connect a batteryterminal to the pc board 138. Because the curing temperature ofconductive epoxy is 125° C., the following process is used: (a) firstcure the conductive epoxy of a battery terminal ribbon to the pc boardwithout the battery, (b) then glue the battery to the pc board usingroom temperature cure silicone, and (c) laser tack weld the connectingribbon to the battery.

Also not shown in FIG. 7 is the manner of connecting the proximal end ofthe feed-through pin 130 to the pc board 138, and connecting a pc boardground pad to the case 124. A preferred method of making theseconnections is to use conductive epoxy and conductive ribbons, althoughother connection methods known in the art may also be used.

Further shown in FIG. 7 is a layer of silicon molding 125 that is usedto cover all surfaces of the entire IEAD 100 except for the anode ringelectrode 120 and the circular cathode electrode 110. An overmoldingprocess is used to accomplish this, although overmolding using siliconeLSR 70 (curing temperature of 120° C.) with an injection moldlingprocess cannot be used. Overmolding processes that may be used include:(a) molding a silicone jacket and gluing the jacket onto the case usingroom temperature cure silicone (RTV) inside of a mold, and curing atroom temperature; (b) injecting room temperature cure silicone in a PEEKor Teflon® mold (silicone will not stick to the Teflon® or PEEKmaterial); or (c) dip coating the IEAD 100 in room temperature curesilicone while masking the electrode surfaces that are not to be coated.(Note: PEEK is a well known semicrystalline thermoplastic with excellentmechanical and chemical resistance properties that are retained at hightemperatures.)

When assembled, the insulating layer 129 is positioned underneath thering anode electrode 120 so that the anode electrode does not short tothe case 124. The only electrical connection made to the anode electrode120 is through the distal tip of the feed-through pin 130. Theelectrical contact with the cathode electrode 110 is made through thecase 124. However, because the entire IEAD is coated with a layer ofsilicone molding 125, except for the anode ring electrode 120 and thecircular cathode electrode 110, all stimulation current generated by theIEAD 100 must flow between the exposed surfaces of the anode andcathode.

It is noted that while the preferred configuration described herein usesa ring anode electrode 120 placed around the edges of the IEAD housing,and a circular cathode electrode 110 placed in the center of the cathodeside of the IEAD case 124, such an arrangement could be reversed, i.e.,the ring electrode could be the cathode, and the circular electrodecould be the anode.

Moreover, the location and shape of the electrodes may be configureddifferently than is shown in the one preferred embodiment describedabove in connection with FIGS. 1, and 2-7. For example, the ring anodeelectrode 120 need not be placed around the perimeter of the device, butsuch electrode may be a flat circumferential electrode that assumesdifferent shapes (e.g., round or oval) that is placed on the front orback surface of the IEAD so as to surround the central electrode.Further, for some embodiments, the surfaces of the anode and cathodeelectrodes may have convex surfaces.

It is also noted that while one preferred embodiment has been disclosedherein that incorporates a round, or short cylindrical-shaped housing,also referred to as a coin-shaped housing, the invention does notrequire that the case 124 (which may also be referred to as a“container”), and its associated cover plate 122, be round. The casecould just as easily be an oval-shaped, rectangular-shaped (e.g., squarewith smooth corners), polygonal-shaped (e.g., hexagon-, octagon-,pentagon-shaped), button-shaped (with convex top or bottom for asmoother profile) device. Some particularly attractive alternate caseshapes, and electrode placement on the surfaces of those case shapes,are illustrated in Appendix E. Any of these alternate shapes, or others,would still permit the basic principles of the invention to be used toprovide a robust, compact, thin, case to house the electronic circuitryand power source used by the invention; as well as to help protect afeed-through assembly from being exposed to excessive heat duringassembly, and to allow the thin device to provide the benefits describedherein related to its manufacture, implantation and use. For example, aslong as the device remains relatively thin, e.g., no more than about 2-3mm, and does not have a maximum linear dimension greater than about 25mm, then the device can be readily implanted in a pocket over the tissuearea where the selected acupuoint(s) is located. As long as there is arecess in the wall around the perimeter of the case wherein thefeed-through assembly may be mounted, which recess effectively moves thewall or edge of the case inwardly into the housing a safe thermaldistance, as well as a safe residual weld stress distance, from theperimeter wall where a hermetically-sealed weld occurs, the principlesof the invention apply.

Further, it should be noted that while the preferred configuration ofthe IEAD described herein utilizes a central electrode on one of itssurfaces that is round, having a diameter of nominally 4 mm, suchcentral electrode need not necessarily be round. It could be ovalshaped, polygonal-shaped, or shaped otherwise, in which case its size isbest defined by its maximum width, which will generally be no greaterthan about 7 mm.

Finally, it is noted that the electrode arrangement may be modifiedsomewhat, and the desired attributes of the invention may still beachieved. For example, as indicated previously, one preferred electrodeconfiguration for use with the invention utilizes a symmetricalelectrode configuration, e.g., an annular electrode of a first polaritythat surrounds a central electrode of a second polarity. Such asymmetrical electrode configuration makes the implantableelectroacupuncture device (IEAD) relatively immune to being implanted inan improper orientation relative to the body tissue at the selectedacupoint(s) that is being stimulated. However, an electrodeconfiguration that is not symmetrical may still be used and many of thetherapeutic effects of the invention may still be achieved. For example,two spaced-apart electrodes on a front surface of the housing, one of afirst polarity, and a second of a second polarity, could still, whenoriented properly with respect to a selected acupoint tissue location,provide some desired therapeutic results

FIG. 7A schematically illustrates a few alternative electrodeconfigurations that may be used with the invention. The electrodeconfiguration schematically shown in the upper left corner of FIG. 7A,identified as “I”, schematically illustrates one central electrode 110surrounded by a single ring electrode 120. This is one of the preferredelectrode configurations that has been described previously inconnection, e.g., with the description of FIG. 1 and FIG. 7, and ispresented in FIG. 7A for reference and comparative purposes.

In the lower left corner of FIG. 7A, identified as “II”, anelectrode/array configuration is schematically illustrated that has acentral electrode 310 of a first polarity surrounded by an electrodearray 320 a of two electrodes of a second polarity. When the twoelectrodes (of the same polarity) in the electrode array 320 a areproperly aligned with the body tissue being stimulated, e.g., alignedwith a nerve 87 (see FIGS. 17A and 17B), then such electrodeconfiguration can stimulate the body tissue (e.g., the nerve 87) at ornear the desired acupoint(s) with the same, or almost the same, efficacyas can the electrode configuration I (upper right corner of FIG. 7A).

Note, as has already been described above, the phrase “electrode orelectrode array,” or “electrodes or electrode arrays,” may also bereferred to herein as “electrode/array” or “electrodes/arrays,”respectively. For the ease of explanation, when an electrode array isreferred to herein that comprises a plurality (two or more) ofindividual electrodes of the same polarity, the individual electrodes ofthe same polarity within the electrode array may also be referred to as“individual electrodes”, “segments” of the electrode array, “electrodesegments”, or just “segments”.

In the lower right corner of FIG. 7A, identified as “III”, en electrodeconfiguration is schematically illustrated that has a centralelectrode/array 310 b of three electrode segments of a first polaritysurrounded by an electrode array 320 b of three electrode segments of asecond polarity. As shown in FIG. 7A-III, the three electrode segmentsof the electrode array 320 b are symmetrically positioned within thearray 320 b, meaning that they are positioned more or less equidistantfrom each other. However, a symmetrical positioning of the electrodesegments within the array is not necessary to stimulate the body tissueat the desired acupoint(s) with some efficacy.

In the upper right corner of FIG. 7A, identified as “IV”, anelectrode/array configuration is schematically illustrated that has acentral electrode array 310 c of a first polarity surrounded by anelectrode array 320 c of four electrode segments of a second polarity.The four electrode segments of the electrode array 320 c are arrangedsymmetrically in a round or oval-shaped array. The four electrodesegments of the electrode array 310 b are likewise arrangedsymmetrically in a round or oval-shaped array. While preferred for manyconfigurations, the use of a symmetrical electrode/array, whether as acentral electrode array 310 or as a surrounding electrode/array 320, isnot always required.

The electrode configurations I, II, III and IV shown schematically inFIG. 7A are only representative of a few electrode configurations thatmay be used with the present invention. Further, it is to be noted thatthe central electrode/array 310 need not have the same number ofelectrode segments as does the surrounding electrode/array 320.Typically, the central electrode/array 310 of a first polarity will be asingle electrode; whereas the surrounding electrode/array 320 of asecond polarity may have n individual electrode segments, where n is aninteger that can vary from 1, 2, 3, . . . n. Thus, for a circumferentialelectrode array where n=4, there are four electrode segments of the samepolarity arranged in circumferential pattern around a centralelectrode/array. If the circumferential electrode array with n=4 is asymmetrical electrode array, then the four electrode segments will bespaced apart equally in a circumferential pattern around a centralelectrode/array. When n=1, the circumferential electrode array reducesto a single circumferential segment or a single annular electrode thatsurrounds a central electrode/array.

Additionally, the polarities of the electrode/arrays may be selected asneeded. That is, while the central electrode/array 310 is typically acathode (−), and the surrounding electrode/array 320 is typically ananode (+), these polarities may be reversed.

It should further be noted that the shape of the circumferentialelectrode/array, whether circular, oval, or other shape, need notnecessarily be the same shape as the IEAD housing, unless thecircumferential electrode/array is attached to a perimeter edge of theIEAD housing. The IEAD housing may be round, or it may be oval, or itmay have a polygon shape, or other shape, as needed to suit the needs ofa particular manufacturer and/or patient.

Additional electrode configurations, both symmetrical electrodeconfigurations and non-symmetrical electrode configurations, that may beused with an EA stimulation device as described herein, are describedand illustrated in Appendix A and Appendix B.

Electrical Design

Next, with reference to FIGS. 8A-14, the electrical design and operationof the circuits employed within the IEAD 100 will be described. Moredetails associated with the design of the electrical circuits describedherein may be found in many of the patent applications referenced abovein Paragraph [0001].

FIG. 8A shows a functional block diagram of an implantableelectroacupuncture device (IEAD) 100 made in accordance with theteachings disclosed herein. As seen in FIG. 8A, the IEAD 100 uses animplantable battery 215 having a battery voltage V_(BAT). Also includedwithin the IEAD 100 is a Boost Converter circuit 200, an Output Circuit202 and a Control Circuit 210. The battery 115, boost converter circuit200, output circuit 202 and control circuit 210 are all housed within anhermetically sealed housing 124.

As controlled by the control circuit 210, the output circuit 202 of theIEAD 100 generates a sequence of stimulation pulses that are deliveredto electrodes E1 and E2, through feed-through terminals 206 and 207,respectively, in accordance with a prescribed stimulation regimen. Acoupling capacitor C_(C) is also employed in series with at least one ofthe feed-through terminals 206 or 207 to prevent DC (direct current)current from flowing into the patient's body tissue.

As explained more fully below in connection with the description ofFIGS. 15A and 15B, the prescribed stimulation regimen comprises acontinuous stream of stimulation pulses having a fixed amplitude (whichcould be either a fixed voltage or a fixed current), a fixed pulsewidth, e.g., 0.5 millisecond, and at a fixed frequency, e.g., 2 Hz,during each stimulation session. The stimulation session, also as partof the stimulation regimen, is generated at a very low duty cycle, e.g.,for 30 minutes once each week. Other stimulation regimens may also beused, e.g., using a variable frequency for the stimulus pulse during astimulation session rather than a fixed frequency.

In one preferred embodiment, the electrodes E1 and E2 form an integralpart of the housing 124. That is, electrode E2 may comprise acircumferential anode electrode that surrounds a cathode electrode E1.The cathode electrode E1, for the embodiment described here, iselectrically connected to the case 124 (thereby making the feed-throughterminal 206 unnecessary).

In a second preferred embodiment, particularly well-suited forimplantable electrical stimulation devices, the anode electrode E2 iselectrically connected to the case 124 (thereby making the feed-throughterminal 207 unnecessary). The cathode electrode E1 is electricallyconnected to the circumferential electrode that surrounds the anodeelectrode E2. That is, the stimulation pulses delivered to the targettissue location (i.e., to the selected acupoint) through the electrodesE1 and E2 are, relative to a zero volt ground (GND) reference, negativestimulation pulses, as shown in the waveform diagram near the lowerright hand corner of FIG. 8A.

Thus, in the embodiment described in FIG. 8A, it is seen that during astimulation pulse the electrode E2 functions as an anode, or positive(+) electrode, and the electrode E1 functions as a cathode, or negative(−) electrode.

The battery 115 provides all of the operating power needed by the EAdevice 100. The battery voltage V_(BAT) is not the optimum voltageneeded by the circuits of the EA device, including the output circuitry,in order to efficiently generate stimulation pulses of amplitude, e.g.,−V_(A) volts. The amplitude V_(A) of the stimulation pulses is typicallymany times greater than the battery voltage V_(BAT). This means that thebattery voltage must be “boosted”, or increased, in order forstimulation pulses of amplitude V_(A) to be generated. Such “boosting”is done using the boost converter circuit 200. That is, it is thefunction of the Boost Converter circuit 200 to take its input voltage,V_(BAT), and convert it to another voltage, e.g., V_(OUT), which voltageV_(OUT) is needed by the output circuit 202 in order for the IEAD 100 toperform its intended function.

The IEAD 100 shown in FIG. 8A, and packaged as described above inconnection with FIGS. 1-7, advantageously provides a tinyself-contained, coin-sized stimulator that may be implanted in a patientat or near a specified acupoint in order to favorably treat a conditionor disease of a patient. The coin-sized stimulator advantageouslyapplies electrical stimulation pulses at very low levels and low dutycycles in accordance with specified stimulation regimens throughelectrodes that form an integral part of the housing of the stimulator.A tiny battery inside of the coin-sized stimulator provides enoughenergy for the stimulator to carry out its specified stimulation regimenover a period of several years. Thus, the coin-sized stimulator, onceimplanted, provides an unobtrusive, needleless, long-lasting, safe,elegant and effective mechanism for treating certain conditions anddiseases that have long been treated by acupuncture orelectroacupuncture.

A boost converter integrated circuit (IC) typically draws current fromits power source in a manner that is proportional to the differencebetween the actual output voltage V_(OUT) and a set point outputvoltage, or feedback signal. A representative boost converter circuitthat operates in this manner is shown in FIG. 8B. At boost converterstart up, when the actual output voltage is low compared to the setpoint output voltage, the current drawn from the power source can bequite large. Unfortunately, when batteries are used as power sources,they have internal voltage losses (caused by the battery's internalimpedance) that are proportional to the current drawn from them. Thiscan result in under voltage conditions when there is a large currentdemand from the boost converter at start up or at high instantaneousoutput current. Current surges and the associated under voltageconditions can lead to undesired behavior and reduced operating life ofan implanted electro-acupuncture device.

In the boost converter circuit example shown in FIG. 8B, the battery ismodeled as a voltage source with a simple series resistance. Withreference to the circuit shown in FIG. 8B, when the series resistanceR_(BAT) is small (5 Ohms or less), the boost converter input voltageV_(IN), output voltage V_(OUT) and current drawn from the battery,I_(BAT), typically look like the waveform shown in FIG. 9A, where thehorizontal axis is time, and the vertical axis on the left is voltage,and the vertical axis of the right is current.

Referring to the waveform in FIG. 9A, at boost converter startup (10ms), there is 70 mA of current drawn from the battery with only ˜70 mVof drop in the input voltage V_(IN) (battery voltage). Similarly, theinstantaneous output current demand for electro-acupuncture pulses drawsup to 40 mA from the battery with an input voltage drop of ˜40 mV.

Disadvantageously, however, a battery with higher internal impedance(e.g., 160 Ohms), cannot source more than a milliampere or so of currentwithout a significant drop in output voltage. This problem is depictedin the timing waveform diagram shown in FIG. 9B. In FIG. 9B, as in FIG.9A, the horizontal axis is time, the left vertical axis is voltage, andthe right vertical axis is current.

As seen in FIG. 9B, as a result of the higher internal batteryimpedance, the voltage at the battery terminal (V_(IN)) is pulled downfrom 2.9 V to the minimum input voltage of the boost converter (˜1.5 V)during startup and during the instantaneous output current loadassociated with electro-acupuncture stimulus pulses. The resulting dropsin output voltage V_(OUT) are just not acceptable in any type of circuitexcept an uncontrolled oscillator circuit.

Also, it should be noted that although the battery used in the boostconverter circuit is modeled in FIG. 8B as a simple series resistor,battery impedance can arise from the internal design, battery electrodesurface area and different types of electrochemical reactions. All ofthese contributors to battery impedance can cause the voltage of thebattery at the battery terminals to decrease as the current drawn fromthe battery increases.

In a suitably small and thin implantable electroacupuncture device(IEAD) of the type disclosed herein, it is desired to use a higherimpedance battery in order to assure a small and thin device, keep costslow, and/or to have low self-discharge rates. The battery internalimpedance also typically increases as the battery discharges. This canlimit the service life of the device even if a new battery hasacceptably low internal impedance. Thus, it is seen that for the IEAD100 disclosed herein to reliably perform its intended function over along period of time, a circuit design is needed for the boost convertercircuit that can manage the instantaneous current drawn from V_(IN) ofthe battery. Such current management is needed to prevent the battery'sinternal impedance from causing V_(IN) (the battery voltage) to drop tounacceptably low levels as the boost converter circuit pumps up theoutput voltage V_(OUT) and when there is high instantaneous outputcurrent demand, as occurs when EA stimulation pulses are generated.

To provide this needed current management, the IEAD 100 disclosed hereinemploys electronic circuitry as shown in FIG. 10, or equivalentsthereof. Similar to what is shown in FIG. 8B, the circuitry of FIG. 10includes a battery, a boost converter circuit 200, an output circuit230, and a control circuit 220. The control circuit 220 generates adigital control signal that is used to duty cycle the boost convertercircuit 200 ON and OFF in order to limit the instantaneous current drawnfrom the battery. That is, the digital control signal pulses the boostconverter ON for a short time, but then shuts the boost converter downbefore a significant current can be drawn from the battery. Inconjunction with such pulsing, an input capacitance C_(F) is used toreduce the ripple in the battery voltage V_(BAT) (which battery voltageis also the input voltage to the boost converter circuit 200, and isthus also referred to herein as the input voltage V_(IN)). The capacitorC_(F) supplies the high instantaneous current for the short time thatthe boost converter is ON and then recharges more slowly from thebattery during the interval that the boost converter is OFF.

A variation of the above-described use of a digital control signal toduty cycle the boost converter circuit 200 ON and OFF is to let thedigital control be generated within the boost converter 200 itself(without having to use a separate control circuit 220). In accordancewith this variation, the boost converter circuit 200 shuts itself downwhenever the battery voltage falls below a predetermined level abovethat required by the remaining circuitry. For example, the MAX8570 boostconverter IC, commercially available from Maxim, shuts down when theapplied voltage falls below 2.5 V. This is still a high enough voltageto ensure the microprocessor and other circuitry remain operational.Thus, as soon as the input voltage drops below 2.5 volts, the boostconverter circuit shuts down, thereby limiting the instantaneous currentdrawn from the battery. When the boost converter shuts down, theinstantaneous battery current drawn from the battery is immediatelyreduced a significant amount, thereby causing the input voltage toincrease. The boost converter remains shut down until the microprocessor(e.g., the circuit U2 shown in FIG. 13A, described below), and/or othercircuitry used with the boost converter, determine that it is time toturn the boost converter back ON. Once turned ON, the boost converterremains ON until, again, the input voltage drops to below 2.5 volts.This pattern continues, with the boost converter being ON for a shorttime, and OFF for a much longer time, thereby controlling and limitingthe amount of current that can be drawn from the battery.

In the circuitry shown in FIG. 10, it is noted that the output voltageV_(OUT) generated by the boost converter circuit 200 is set by thereference voltage V_(REF) applied to the set point or feedback terminalof the boost converter circuit 200. For the configuration shown in FIG.10, V_(REF) is proportional to the output voltage V_(OUT), as determinedby the resistor dividing network of R1 and R2.

The switches S_(P) and S_(R), shown in FIG. 10 as part of the outputcircuit 230, may also be controlled by the control circuit 220. Theseswitches are selectively closed and opened to form the EA stimulationpulses applied to the load, R_(LOAD). Before a stimulus pulse occurs,switch S_(R) is closed sufficiently long for the circuit side ofcoupling capacitor C_(C) to be charged to the output voltage, V_(OUT).The tissue side of C_(C) is maintained at 0 volts by the cathodeelectrode E2, which is maintained at ground reference. Then, for most ofthe time between stimulation pulses, both switches S_(R) and S_(P) arekept open, with a voltage approximately equal to the output voltageV_(OUT) appearing across the coupling capacitor C_(C).

At the leading edge of a stimulus pulse, the switch Sp is closed, whichimmediately causes a negative voltage −V_(OUT) to appear across theload, R_(LOAD), causing the voltage at the anode E1 to also drop toapproximately −V_(OUT), thereby creating the leading edge of thestimulus pulse. This voltage starts to decay back to 0 volts ascontrolled by an RC (resistor-capacitance) time constant that is longcompared with the desired pulse width. At the trailing edge of thepulse, before the voltage at the anode E1 has decayed very much, theswitch S_(P) is open and the switch S_(R) is closed. This action causesthe voltage at the anode E1 to immediately (relatively speaking) returnto 0 volts, thereby defining the trailing edge of the pulse. With theswitch S_(R) closed, the charge on the circuit side of the couplingcapacitor C_(C) is allowed to charge back to V_(OUT) within a timeperiod controlled by a time constant set by the values of capacitorC_(C) and resistor R3. When the circuit side of the coupling capacitorC_(C) has been charged back to V_(OUT), then switch S_(R) is opened, andboth switches S_(R) and S_(P) remain open until the next stimulus pulseis to be generated. Then the process repeats each time a stimulus pulseis to be applied across the load.

Thus, it is seen that in one embodiment of the electronic circuitry usedwithin the IEAD 100, as shown in FIG. 10, a boost converter circuit 200is employed which can be shut down with a control signal. The controlsignal is ideally a digital control signal generated by a controlcircuit 220 (which may be realized using a microprocessor or equivalentcircuit). The control signal is applied to the low side (ground side) ofthe boost converter circuit 200 (identified as the “shutdown” terminalin FIG. 10). A capacitor C_(F) supplies instantaneous current for theshort ON time that the control signal enables the boost convertercircuit to operate. And, the capacitor CF is recharged from the batteryduring the relatively long OFF time when the control signal disables theboost converter circuit.

An alternate embodiment of the electronic circuitry that may be usedwithin the IEAD 100 is shown in FIG. 11. This circuit is in mostrespects the same as the circuitry shown in FIG. 10. However, in thisalternate embodiment shown in FIG. 11, the boost converter circuit 200does not have a specific shut down input control. Rather, as seen inFIG. 11, the boost converter circuit is shut down by applying a controlvoltage to the feedback input of the boost converter circuit 200 that ishigher than V_(REF). When this happens, i.e., when the control voltageapplied to the feedback input is greater than V_(REF), the boostconverter will stop switching and draws little or no current from thebattery. The value of V_(REF) is typically a low enough voltage, such asa 1.2 V band-gap voltage, that a low level digital control signal can beused to disable the boost converter circuit. To enable the boostconverter circuit, the control signal can be set to go to a highimpedance, which effectively returns the node at the V_(REF) terminal tothe voltage set by the resistor divider network formed from R1 and R2.Alternatively the control signal can be set to go to a voltage less thanV_(REF).

A low level digital control signal that performs this function ofenabling (turning ON) or disabling (turning OFF) the boost convertercircuit is depicted in FIG. 11 as being generated at the output of acontrol circuit 220. The signal line on which this control signal ispresent connects the output of the control circuit 220 with the V_(REF)node connected to the feedback input of the boost converter circuit.This control signal, as suggested by the waveform shown in FIG. 11,varies from a voltage greater than V_(REF), thereby disabling or turningOFF the boost converter circuit, to a voltage less than V_(REF), therebyenabling or turning the boost converter circuit ON.

A refinement to the alternate embodiment shown in FIG. 11 is to use thecontrol signal to drive the low side of R2 as shown in FIG. 12. That is,as shown in FIG. 12, the boost converter circuit 200 is shut down whenthe control signal is greater than V_(REF) and runs when the controlsignal is less than V_(REF). A digital control signal can be used toperform this function by switching between ground and a voltage greaterthan V_(REF). This has the additional possibility of delta-sigmamodulation control of V_(OUT) if a measurement of the actual V_(OUT) isavailable for feedback, e.g., using a signal line 222, to thecontroller.

One preferred embodiment of the circuitry used in an implantableelectroacupuncture device (IEAD) 100 that employs a digital controlsignal as taught herein is shown in the schematic diagram shown in FIG.13A. In FIG. 13A, there are basically four integrated circuits (ICs)used as the main components. The IC U1 is a boost converter circuit, andperforms the function of the boost converter circuit 200 describedpreviously in connection with FIGS. 8B, 10, 11 and 12.

The IC U2 is a micro-controller IC and is used to perform the functionof the control circuit 220 described previously in connection with FIGS.10, 11 and 12. A preferred IC for this purpose is a MSP430G24521micro-controller chip made by Texas Instruments. This chip includes 8 KBof Flash memory. Having some memory included with the micro-controlleris important because it allows the parameters associated with a selectedstimulation regimen to be defined and stored. One of the advantages ofthe IEAD described herein is that it provides a stimulation regimen thatcan be defined with just 5 parameters, as taught below in connectionwith FIGS. 15A and 15B. This allows the programming features of themicro-controller to be carried out in a simple and straightforwardmanner.

The micro-controller U2 primarily performs the function of generatingthe digital signal that shuts down the boost converter to prevent toomuch instantaneous current from being drawn from the battery V_(BAT),for those embodiments of the invention where this function is needed.The micro-controller U2 also controls the generation of the stimuluspulses at the desired pulse width and frequency. It further keeps trackof the time periods associated with a stimulation session, i.e., when astimulation session begins and when it ends.

The micro-controller U2 also controls the amplitude of the stimuluspulse. This is done by adjusting the value of a current generated by aProgrammable Current Source U3. In one embodiment, U3 is realized with avoltage controlled current source IC. In such a voltage controlledcurrent source, the programmed current is set by a programmed voltageappearing across a fixed resistor R5, i.e., the voltage appearing at the“OUT” terminal of U3. This programmed voltage, in turn, is set by thevoltage applied to the “SET” terminal of U3. That is, the programmedcurrent source U3 sets the voltage at the “OUT” terminal to be equal tothe voltage applied to the “SET” terminal. The programmed current thatflows through the resistor R5 is then set by Ohms Law to be the voltageat the “set” terminal divided by R5. As the voltage at the “set”terminal changes, the current flowing through resistor R5 at the “OUT”terminal changes, and this current is essentially the same as thecurrent pulled through the closed switch M1, which is essentially thesame current flowing through the load R_(LOAD). Hence, whatever currentflows through resistor R5, as set by the voltage across resistor R5, isessentially the same current that flows through the load R_(LOAD). Thus,as the micro-controller U2 sets the voltage at the “set” terminal of U3,on the signal line labeled “AMPSET”, it controls what current flowsthrough the load R_(LOAD). In no event can the amplitude of the voltagepulse developed across the load R_(LOAD) exceed the voltage V_(OUT)developed by the boost converter less the voltage drops across theswitches and current source.

The switches S_(R) and S_(P) described previously in connection withFIGS. 10, 11 and 12 are realized with transistor switches M1, M2, M3,M4, M5 and M6, each of which is controlled directly or indirectly bycontrol signals generated by the micro-controller circuit U2. For theembodiment shown in FIG. 13A, these switches are controlled by twosignals, one appearing on signal line 234, labeled PULSE, and the otherappearing on signal line 236, labeled RCHG (which is an abbreviation for“recharge”). For the circuit configuration shown in FIG. 13A, the RCHGsignal on signal line 236 is always the inverse of the PULSE signalappearing on signal line 234. This type of control does not allow bothswitch M1 and switch M2 to be open or closed at the same time. Rather,switch M1 is closed when switch M2 is open, and switch M2 is closed,when switch M1 is open. When switch M1 is closed, and switch M2 is open,the stimulus pulse appears across the load, R_(LOAD), with the currentflowing through the load, R_(LOAD), being essentially equal to thecurrent flowing through resistor R5. When the switch M1 is open, andswitch M2 is closed, no stimulus pulse appears across the load, and thecoupling capacitors C5 and C6 are recharged through the closed switch M2and resistor R6 to the voltage V_(OUT) in anticipation of the nextstimulus pulse.

The circuitry shown in FIG. 13A is only exemplary of one type of circuitthat may be used to control the pulse width, amplitude, frequency, andduty cycle of stimulation pulses applied to the load, R_(LOAD). Any typeof circuit, or control, that allows stimulation pulses of a desiredmagnitude (measured in terms of pulse width, frequency and amplitude,where the amplitude may be measured in current or voltage) to be appliedthrough the electrodes to the patient at the specified acupoint at adesired duty cycle (stimulation session duration and frequency) may beused. However, for the circuitry to perform its intended function over along period of time, e.g., years, using only a small energy source,e.g., a small coin-sized battery having a high battery impedance and arelatively low capacity, the circuitry must be properly managed andcontrolled to prevent excessive current draw from the battery.

It is also important that the circuitry used in the IEAD 100, e.g., thecircuitry shown in FIGS. 10, 11, 12, 13A, or equivalents thereof, havesome means for controlling the stimulation current that flows throughthe load, R_(LOAD), which load may be characterized as the patient'stissue impedance at and around the acupoint being stimulated. Thistissue impedance, as shown in FIGS. 11 and 12, may typically vary frombetween about 300 ohms to 2000 ohms. Moreover, it not only varies fromone patient to another, but it varies over time. Hence, there is a needto control the current that flows through this variable load, R_(LOAD).One way of accomplishing this goal is to control the stimulationcurrent, as opposed to the stimulation voltage, so that the same currentwill flow through the tissue load regardless of changes that may occurin the tissue impedance over time. The use of a voltage controlledcurrent source U3, as shown in FIG. 13A, is one way to satisfy thisneed.

Still referring to FIG. 13A, a fourth IC U4 is connected to themicro-controller U2. For the embodiment shown in FIG. 13A, the IC U4 isan electromagnetic field sensor, and it allows the presence of anexternally-generated (non-implanted) electromagnetic field to be sensed.An “electromagnetic” field, for purposes of this application includesmagnetic fields, radio frequency (RF) fields, light fields, and thelike. The electromagnetic sensor may take many forms, such as anywireless sensing element, e.g., a pickup coil or RF detector, a photondetector, a magnetic field detector, and the like. When a magneticsensor is employed as the electromagnetic sensor U4, the magnetic fieldis generated using an External Control Device (ECD) 240 thatcommunicates wirelessly, e.g., through the presence or absence of amagnetic field, with the magnetic sensor U4. (A magnetic field, or othertype of field if a magnetic field is not used, is symbolicallyillustrated in FIG. 13A by the wavy line 242.) In its simplest form, theECD 240 may simply be a magnet, and modulation of the magnetic field isachieved simply by placing or removing the magnet next to or away fromthe IEAD. When other types of sensors (non-magnetic) are employed, theECD 240 generates the appropriate signal or field to be sensed by thesensor that is used.

Use of the ECD 240 provides a way for the patient, or medical personnel,to control the IEAD 100 after it has been implanted (or before it isimplanted) with some simple commands, e.g., turn the IEAD ON, turn theIEAD OFF, increase the amplitude of the stimulation pulses by oneincrement, decrease the amplitude of the stimulation pulses by oneincrement, and the like. A simple coding scheme may be used todifferentiate one command from another. For example, one coding schemeis time-based. That is, a first command is communicated by holding amagnet near the IEAD 100, and hence near the magnetic sensor U4contained within the IEAD 100, for differing lengths of time. If, forexample, a magnet is held over the IEAD for at least 2 seconds, but nomore than 7 seconds, a first command is communicated. If a magnet isheld over the IEAD for at least 11 seconds, but no more than 18 seconds,a second command is communicated, and so forth.

Another coding scheme that could be used is a sequence-based codingscheme. That is, application of 3 magnetic pulses may be used to signalone external command, if the sequence is repeated 3 times. A sequence of2 magnetic pulses, repeated twice, may be used to signal anotherexternal command. A sequence of one magnetic pulse, followed by asequence of two magnetic pulses, followed by a sequence of threemagnetic pulses, may be used to signal yet another external command.

Other simple coding schemes may also be used, such as the letters AA,RR, HO, BT, KS using international Morse code. That is, the Morse codesymbols for the letter “A” are dot dash, where a dot is a short magneticpulse, and a dash is a long magnetic pulse. Thus, to send the letter Ato the IEAD 100 using an external magnet, the user would hold the magnetover the area where the IEAD 100 is implanted for a short period oftime, e.g., one second or less, followed by holding the magnet over theIEAD for a long period of time, e.g., more than one second.

More sophisticated magnetic coding schemes may be used to communicate tothe micro-controller chip U2 the operating parameters of the IEAD 100.For example, using an electromagnet controlled by a computer, the pulsewidth, frequency, and amplitude of the EA stimulation pulses used duringeach stimulation session may be pre-set. Also, the frequency of thestimulation sessions can be pre-set. Additionally, a master reset signalcan be sent to the device in order to re-set these parameters to defaultvalues. These same operating parameters and commands may be re-sent atany time to the IEAD 100 during its useful lifetime should changes inthe parameters be desired or needed.

The current and voltage waveforms associated with the operation of theIEAD circuitry of FIG. 13A are shown in FIG. 13B. In FIG. 13B, thehorizontal axis is time, the left vertical axis is voltage, and theright vertical axis is current. The battery in this example has 160 Ohmsof internal impedance.

Referring to FIGS. 13A and 13B, during startup, the boost converter ONtime is approximately 30 microseconds applied every 7.8 milliseconds.This is sufficient to ramp the output voltage V_(OUT) up to over 10 Vwithin 2 seconds while drawing no more than about 1 mA from the batteryand inducing only 150 mV of input voltage ripple.

The electroacupuncture (EA) simulation pulses resulting from operationof the circuit of FIG. 13A have a width of 0.5 milliseconds and increasein amplitude from approximately 1 mA in the first pulse to approximately15 mA in the last pulse. The instantaneous current drawn from thebattery is less than 2 mA for the EA pulses and the drop in batteryvoltage is less than approximately 300 mV. The boost converter isenabled (turned ON) only during the instantaneous output current surgesassociated with the 0.5 milliseconds wide EA pulses.

Another preferred embodiment of the circuitry used in an implantableelectroacupuncture device (IEAD) 100 that employs a digital controlsignal as taught herein is shown in the schematic diagram of FIG. 14.The circuit shown in FIG. 14 is, in most respects, very similar to thecircuit described previously in connection with FIG. 13A. What is new inFIG. 14 is the inclusion of an external Schottky diode D4 at the outputterminal LX of the boost convertor U1 and the inclusion of a fifthintegrated circuit (IC) U5 that essentially performs the same functionas the switches M1-M6 shown in FIG. 13A.

The Schottky diode D5 helps isolate the output voltage V_(OUT) generatedby the boost converter circuit U1. This is important in applicationswhere the boost converter circuit U1 is selected and operated to providean output voltage V_(OUT) that is four or five times (or more) as greatas the battery voltage, V_(BAT). For example, in the embodiment forwhich the circuit of FIG. 14 is designed, the output voltage V_(OUT) isdesigned to be nominally 15 volts using a battery that has a nominalbattery voltage of only 3 volts. (In contrast, the embodiment shown inFIG. 13A is designed to provide an output voltage that is nominally10-12 volts, using a battery having a nominal output voltage of 3volts.)

The inclusion of the fifth IC U5 in the circuit shown in FIG. 14 is, asindicated, used to perform the function of a switch. The other ICs shownin FIG. 14, U1 (boost converter), U2 (micro-controller), U3 (voltagecontrolled programmable current source) and U4 (electromagnetic sensor)are basically the same as the IC's U1, U2, U3 and U4 describedpreviously in connection with FIG. 13A.

The IC U5 shown in FIG. 14 functions as a single pole/double throw(SPDT) switch. Numerous commercially-available ICs may be used for thisfunction. For example, an ADG1419 IC, available from Analog DevicesIncorporated (ADI) may be used. In such IC U5, the terminal “D”functions as the common terminal of the switch, and the terminals “SA”and “SB” function as the selected output terminal of the switch. Theterminals “IN” and “EN” are control terminals to control the position ofthe switch. Thus, when there is a signal present on the PULSE line,which is connected to the “IN” terminal of U5, the SPDT switch U5connects the “D” terminal to the “SB” terminal, and the SPDT switch U5effectively connects the cathode electrode E1 to the programmablecurrent source U3. This connection thus causes the programmed current,set by the control voltage AMPSET applied to the SET terminal of theprogrammable current source U3, to flow through resistor R5, which inturn causes essentially the same current to flow through the load,R_(LOAD), present between the electrodes E1 and E2. When a signal is notpresent on the PULSE line, the SPDT switch U5 effectively connects thecathode electrode E1 to the resistor R6, which allows the couplingcapacitors C12 and C13 to recharge back to the voltage V_(OUT) providedby the boost converter circuit U2.

From the above description, it is seen that an implantable IEAD 100 isprovided that uses a digital control signal to duty-cycle limit theinstantaneous current drawn from the battery by a boost converter. Threedifferent exemplary configurations (FIGS. 10, 11 and 12) are taught forachieving this desired result, and two exemplary circuit designs thatmay be used to realize this result have been disclosed (FIGS. 13A and14). One configuration (FIG. 12) teaches the additional capability todelta-sigma modulate the boost converter output voltage.

Delta-sigma modulation is well described in the art. Basically, it is amethod for encoding analog signals into digital signals orhigher-resolution digital signals into lower-resolution digital signals.The conversion is done using error feedback, where the differencebetween the two signals is measured and used to improve the conversion.The low-resolution signal typically changes more quickly than thehigh-resolution signal and it can be filtered to recover the highresolution signal with little or no loss of fidelity. Delta-sigmamodulation has found increasing use in modern electronic components suchas converters, frequency synthesizers, switched-mode power supplies andmotor controllers. See, e.g., Wikipedia, Delta-sigma modulation.

II. F. Use and Operation

With the implantable electroacupuncture device (IDEA) 100 in hand, theIDEA 100 may be used most effectively to treat Parkinson's diseaseand/or Essential Tremor by first pre-setting stimulation parameters thatthe device will use during a stimulation session. FIG. 15A shows atiming waveform diagram illustrating the EA stimulation parameters usedby the IEAD to generate EA stimulation pulses. As seen in FIG. 15A,there are basically four parameters associated with a stimulationsession. The time T1 defines the duration (or pulse width) of a stimuluspulse. The time T2 defines the time between the start of one stimuluspulse and the start of the next stimulus pulse. The time T2 thus definesthe period associated with the frequency of the stimulus pulses. Thefrequency of the stimulation pulses is equal to 1/T2. The ratio of T1/T2is typically quite low, e.g., less than 0.01. The duration of astimulation session is defined by the time period T3. The amplitude ofthe stimulus pulses is defined by the amplitude A1. This amplitude maybe expressed in either voltage or current.

Turning next to FIG. 15B, a timing waveform diagram is shown thatillustrates the manner in which the stimulation sessions areadministered in accordance with a preferred stimulation regimen. FIG.15B shows several stimulation sessions of duration T3, and how often thestimulation sessions occur. The stimulation regimen thus includes a timeperiod T4 which sets the time period from the start of one stimulationsession to the start of the next stimulation session. T4 thus is theperiod of the stimulation session frequency, and the stimulation sessionfrequency is equal to 1/T4.

In order to allow the applied stimulation to achieve its desired effecton the body tissue at the selected target stimulation site, the periodof the stimulation session T4 may be varied when the stimulationsessions are first applied. This can be achieved by employing a simplealgorithm within the circuitry of the EA device that changes the valueof T4 in an appropriate manner. For example, at start up, the period T4may be set to a minimum value, T4(min). Then, as time goes on, the valueof T4 is gradually increased until a desired value of T4, T4(final), isreached.

By way of example, if T4(min) is 1 day, and T4(final) is 7 days, thevalue of T4 may vary as follows once the stimulation sessions begin:T4=1 day for the duration between the first and second stimulationsessions, then 2 days for the duration between the second and thirdstimulation sessions, then 4 days for the duration between the third andfourth stimulation sessions, and then finally 7 days for the durationbetween all subsequent stimulation sessions after the fourth stimulationsession.

Rather than increasing the value of T4 from a minimum value to a maximumvalue using a simple doubling algorithm, as described in the previousparagraph, an enhancement is to use a table of session durations andintervals whereby the automatic session interval can be shorter for thefirst week or so. For example the 1^(st) 30 minute session could bedelivered after 1 day. The 2^(nd) 30 minute session could be deliveredafter 2 days. The 3^(rd) 30 minute session could be delivered after 4days. Finally, the 4^(th) 30 minute session could be delivered for allsubsequent sessions after 7 days.

If a triggered session is delivered completely, it advances the therapyschedule to the next table entry.

Another enhancement is that the initial set amplitude only takes effectif the subsequent triggered session is completely delivered. If thefirst session is aborted by a magnet application, or by some othercontrol mechanism, the device reverts to a Shelf Mode. In this way, thefirst session is always a triggered session that occurs in the cliniciansetting.

Finally, the amplitude and place in the session table are saved innon-volatile memory when they change. This avoids a resetting of thetherapy schedule and need to reprogram the amplitude in the event of adevice reset.

One preferred set of parameters to use to define a stimulation regimenare

T1=0.5 milliseconds

T2=500 milliseconds

T3=60 minutes

T4=7 days (10,080 minutes)

A1=12 volts (across 1 kOhm), or 12 milliamperes (mA)

It is to be emphasized that the values shown above for the stimulationregimen are representative of only one preferred stimulation regimenthat could be used. Other stimulation regimens that could be used, andthe ranges of values that could be used for each of these parameters,are as defined in the claims.

It is also emphasized that the ranges of values presented in the claimsfor the parameters used with the invention have been selected after manymonths of careful research and study, and are not arbitrary. Forexample, the ratio of T3/T4, which sets the duty cycle, has beencarefully selected to be very low, e.g., no more than 0.05. Maintaininga low duty cycle of this magnitude represents a significant change overwhat others have attempted in the implantable stimulator art. Not onlydoes a very low duty cycle allow the battery itself to be small (coincell size), which in turn allows the IEAD housing to be very small,which makes the IEAD ideally suited for being used without leads,thereby making it relatively easy to implant the device at the desiredacupuncture site, but it also limits the frequency and duration ofstimulation sessions.

Limiting the frequency and duration of the stimulation sessions is a keyaspect of applicants' invention because it recognizes that sometreatments, such as treating Parkinson's disease and/or EssentialTremor, are best done slowly and methodically, over time, rather thanquickly and harshly using large doses of stimulation (or othertreatments) aimed at forcing a rapid change in the patient's condition.Moreover, applying treatments slowly and methodically is more in keepingwith traditional acupuncture methods (which, as indicated previously,are based on over 2500 years of experience). In addition, this slow andmethodical conditioning is consistent with the time scale for remodelingof the central nervous system needed to produce the sustainedtherapeutic effect. Thus, applicants have based their treatment regimenson the slow-and-methodical approach, as opposed to theimmediate-and-forced approach adopted by many, if not most, prior artimplantable electrical stimulators.

Once the stimulation regimen has been defined and the parametersassociated with it have been pre-set into the memory of themicro-controller circuit 220, the IEAD 100 needs to be implanted.Implantation is usually a simple procedure, and is described above inconnection with the description of FIGS. 1A. 1B, 1C and 1D, as well asFIGS. 17A and/or 17B.

For treating Parkinson's disease and Essential Tremor, the specifiedacupoint(s) (or target tissue locations) at which the EA stimulationpulses should be applied in accordance with a selected stimulationregimen are selected from the group of acupoints that comprise GB34 andGV20.

After implantation, the IEAD must be turned ON, and otherwisecontrolled, so that the desired stimulation regimen may be carried out.In one preferred embodiment, control of the IEAD after implantation, aswell as anytime after the housing of the IEAD has been hermeticallysealed, is performed as shown in the state diagram of FIG. 16. Eachcircle shown in FIG. 16 represents a “state” that the micro-controllerU2 (in FIG. 13A or 14) may operate in under the conditions specified. Asseen in FIG. 16, the controller U2 only operates in one of six states:(1) a “Set Amplitude” state, (2) a “Shelf Mode” state, (3) a “TriggeredSession” state, (4) a “Sleep” state, (5) an “OFF” state, and an (6)“Automatic Session” state. The “Automatic Session” state is the statethat automatically carries out the stimulation regimen using thepre-programmed parameters that define the stimulation regimen.

Shelf Mode is a low power state in which the IEAD is placed prior toshipment. After implant, commands are made through magnet application.Magnet application means an external magnet, typically a small hand-heldcylindrical magnet, is placed over the location where the IEAD has beenimplanted. With a magnet in that location, the magnetic sensor U4 sensesthe presence of the magnet and notifies the controller U2 of themagnet's presence.

From the “Shelf Mode” state, a magnet application for 10 seconds (M.10s)puts the IEAD in the “Set Amplitude” state. While in the “Set Amplitude”state, the stimulation starts running by generating pulses at zeroamplitude, incrementing every five seconds until the patient indicatesthat a comfortable level has been reached. At that time, the magnet isremoved to set the amplitude.

If the magnet is removed and the amplitude is non-zero ( M̂A), the devicecontinues into the “Triggered Session” so the patient receives theinitial therapy. If the magnet is removed during “Set Amplitude” whilethe amplitude is zero ( M̂Â), the device returns to the Shelf Mode.

The Triggered Session ends and stimulation stops after the session time(T_(S)) has elapsed and the device enters the “Sleep” state. If a magnetis applied during a Triggered Session (M), the session aborts to the“OFF” state. If the magnet remains held on for 10 seconds (M.10s) whilein the “OFF” state, the “Set Amplitude” state is entered with thestimulation level starting from zero amplitude as described.

If the magnet is removed ( M) within 10 seconds while in the OFF state,the device enters the Sleep state. From the Sleep state, the deviceautomatically enters the Automatic Session state when the sessioninterval time has expired (T_(I)). The Automatic Session deliversstimulation for the session time (T_(S)) and the device returns to theSleep state. In this embodiment, the magnet has no effect once theAutomatic Session starts so that the full therapy session is delivered.

While in the Sleep state, if a magnet has not been applied in the last30 seconds (D) and a magnet is applied for a window between 20-25seconds and then removed (M.20:25s), a Triggered Session is started. Ifthe magnet window is missed (i.e. magnet removed too soon or too late),the 30 second de-bounce period (D) is started. When de-bounce is active,no magnet must be detected for 30 seconds before a Triggered Session canbe initiated.

The session interval timer runs while the device is in Sleep state. Thesession interval timer is initialized when the device is woken up fromShelf Mode and is reset after each session is completely delivered. Thisabort of a triggered session by magnet application will not reset thetimer, the Triggered Session must be completely delivered.

The circuitry that sets the various states shown in FIG. 16 as afunction of externally-generated magnetic control commands, or otherexternally-generated command signals, is the micro-controller U2 (FIG.14), the processor U2 (FIG. 13A), or the control circuit 220 (FIGS. 10,11 and 12). Such processor-type circuits are programmable circuits thatoperate as directed by a program. The program is often referred to as“code”, or a sequence of steps that the processor circuit follows. The“code” can take many forms, and be written in many different languagesand formats, known to those of skill in the art. Representative “code”for the micro-controller U2 (FIG. 14) for controlling the states of theIEAD as shown in FIG. 16 is found in Appendix C.

In the preceding description, various exemplary embodiments have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe scope of the invention as set forth in the claims that follow. Forexample, certain features of one embodiment described herein may becombined with or substituted for features of another embodimentdescribed herein. The description and drawings are accordingly to beregarded in an illustrative rather than a restrictive sense and are notintended to be exhaustive or to limit the invention to any precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. Thus, while the invention(s) herein disclosed has(have) been described by means of specific embodiments and applicationsthereof, numerous modifications and variations could be made thereto bythose skilled in the art without departing from the scope of theinvention(s) set forth in the claims.

What is claimed is:
 1. An Implantable ElectroAcupuncture System (IEAS)for treating Parkinson's disease or Essential Tremor through applicationof electroacupuncture (EA) stimulation pulses applied at a specifiedtissue location of a patient, comprising: an implantableelectroacupuncture (EA) device comprising a small, hermetically-sealedhousing containing a primary power source, pulse generation circuitrypowered by the primary power source, and a sensor that wirelessly sensesoperating commands generated external to the housing, wherein the pulsegeneration circuitry generates stimulation pulses in accordance with aspecified stimulation regimen as controlled at least in part by theoperating commands sensed through the sensor; a plurality of electrodearrays, where at least one electrode array of the plurality of electrodearrays functions as a cathodic electrode array and at least oneelectrode array of the plurality of electrode arrays functions as ananodic electrode array, wherein an electrode array comprises an array ofn conductive contacts electrically joined together to function jointlyas one electrode, where n is an integer of from 1 to 24, on the outsideof the EA device housing electrically coupled to the pulse generationcircuitry on the inside of the EA device housing through at least onefeed-through terminal passing through a wall of the hermetically-sealedhousing, whereby the stimulation pulses generated by the pulsegeneration circuitry are directed to flow through the patient's tissueat the specified tissue location as such pulses flow between the anodicand cathodic electrode arrays on the outside of the EA device housing inaccordance with the specified stimulation regimen; wherein the specifiedstimulation regimen defines how often a stimulation session comprising astream of stimulation pulses is applied to the patient, the stimulationregimen requiring that the stimulation session have a duration of T3minutes and a rate of occurrence of once every T4 minutes, wherein theratio of T3/T4 is no greater than 0.05; and wherein the specified tissuelocation whereat EA stimulation pulses are applied comprises a targettissue location defined by at least one of acupoints GV20 or GB34. 2.The IEAS of claim 1 wherein the plurality of electrode arrays arelocated on an outside surface of the case of the implantable EA device.3. The IEAS of claim 2 wherein the plurality of electrode arrays arelocated on a bottom surface of the case of the implantable EA device. 4.The IEAS of claim 3 wherein a first one of the plurality of electrodearrays is centrally located on the bottom surface of the case of theimplantable EA device and a second one of the plurality of electrodearrays surrounds the first array.
 5. The IEAS of claim 1 wherein thedimensions of the EA device are L×W×H, where L is the longest lineardimension, W is the shortest linear dimension measured in substantiallythe same plane as L, and H is the maximum height or thickness of thehousing measured in a plane orthogonal with the plane where L and W aremeasured, and wherein L is no greater than about 25 mm, W is no lessthan about 15 mm and H is no greater than about 2.5 mm.
 6. The IEAS ofclaim 1 wherein the primary power source of the EA device comprises abattery having a nominal output voltage of no more than 3.0 volts and aninternal impedance of no less than about 5 ohms.
 7. The IEAS of claim 6wherein the pulse generation circuitry includes: a boost convertercircuit that boosts the nominal voltage of the primary battery to anoutput voltage V_(OUT) that is at least three times the nominal batteryvoltage; a control circuit that selectively turns the boost convertercircuit OFF and ON to limit the amount of current that may be drawn fromthe primary battery; and an output circuit powered by V_(OUT) andcontrolled by the control circuit that generates the stimulation pulsesas defined by the specified stimulation regimen.
 8. The IEAS of claim 7wherein the stimulation pulses generated by the pulse generation circuitand delivered through the plurality of electrode arrays into a load atthe specified tissue location comprise voltage pulses having a voltageamplitude of no less than about 1V and no greater than about 15 V. 9.The IEAS of claim 7 wherein the stimulation pulses generated by thepulse generation circuit and delivered through the plurality ofelectrode arrays into a load at the specified tissue location comprisecurrent pulses having a current amplitude of no less than about 1milliampere (mA) and no greater than about 25 mA.
 10. The IEAS of claim7 wherein the primary battery has sufficient capacity to power the pulsegeneration circuitry in accordance with the specified stimulationregimen for a minimum of 2 years.
 11. The IEAS of claim 1 furtherincluding an external control device adapted to selectively generateoperating commands that are sensed by the sensor within the implantableEA device.
 12. The IEAS of claim 11 wherein the sensor within theimplantable EA device comprises a magnetic field sensor, and wherein theexternal control device comprises a magnet.
 13. An ImplantableElectroAcupuncture Device (IEAD) for treating a Parkinson's or EssentialTremor condition of a patient, comprising a) an implantableelectroacupuncture (EA) device housing having a maximum linear dimensionof no more than 25 mm in a first plane, and a maximum height of no more2.5 mm in a second plane orthogonal to the first plane; b) a primarybattery within the EA housing having an internal impedance of no lessthan about 5 ohms; c) pulse generation circuitry within the EA housingand powered by the primary battery that generates stimulation pulsesduring a stimulation session; d) control circuitry within the EA housingand powered by the primary battery that controls the frequency of thestimulation sessions to occur no more than once every T4 minutes, andthat further controls the duration of each stimulation session to lastno longer than T3 minutes, where the ratio of T3/T4 is no greater than0.05; e) sensor circuitry within the EA housing and coupled to thecontrol circuitry that is responsive to the presence of a controlcommand generated external to the EA device housing, which controlcommand when received by the control circuitry sets the times T3 and T4to appropriate values; and f) a plurality of electrodes located outsideof the EA device housing that are electrically coupled to the pulsegeneration circuitry within the EA device housing, wherein stimulationpulses of the stimulation sessions are applied to body tissue located inthe vicinity of the plurality of electrodes; and g) wherein theplurality of electrodes are positioned to lie at or near a target tissuelocation belonging to the group of target tissue locations comprisingacupoints GV20 or GB34.
 14. The IEAD of claim 13 wherein the sensorcircuitry within the EA housing comprise magnetic field sensingcircuitry, and wherein the control command is derived from the timingassociated with when a magnetic field is present or absent.
 15. A methodfor treating Parkinson's disease or Essential Tremor of a patient,comprising the steps of: (a) implanting an electroacupuncture (EA)device in the patient below the patient's skin at or near at least onespecified target tissue location; (b) enabling the EA device to generatestimulation sessions at a duty cycle that is less than or equal to 0.05,wherein each stimulation session comprises a series of stimulationpulses, wherein the duty cycle is the ratio of T3/T4, where T3 is theduration of each stimulation session, and T4 is the duration betweenstimulation sessions; and (c) delivering the stimulation pulses of eachstimulation session to the at least one specified target tissue locationthrough a plurality of electrode arrays electrically connected to the EAdevice, where an electrode array comprises an array of n conductivecontacts electrically joined together to function jointly as oneelectrode, where n is an integer.
 16. The method of treating Parkinson'sdisease or Essential Tremor of claim 15 wherein the at least onespecified target tissue location at which the stimulation pulses areapplied is selected from the group of target tissue locations comprisingacupoints GV20 or GB34.
 17. The method of treating Parkinson's Diseaseor Essential Tremor of claim 16 further comprising attaching theplurality of electrode arrays to an outside surface of the EA device,with one electrode array of the plurality of electrode arrays comprisinga central electrode array, and with another electrode array of theplurality of electrode arrays comprising an annular electrode array thatsurrounds the central electrode array, and wherein the spacing betweenthe center of the central electrode array and the closest electrodecontact within the annular electrode array comprises at least 5 mm. 18.The method of treating Parkinson's disease or Essential Tremor of claim17 further including setting the time T4, the time between stimulationsessions, to be at least 1440 minutes [1 day] but no longer than 20,160minutes [14 days].
 19. A method of treating Parkinson's disease orEssential Tremor of a patient using a small implantableelectroacupuncture device (IEAD) powered by a small disc primary batteryhaving a specified nominal output voltage of about 3 volts, and havingan internal impedance of at least 5 ohms, the IEAD being configured,using electronic circuitry within the IEAD, to generate stimulationpulses in accordance with a specified stimulation regimen and apply thestimulation pulses through at least two electrodes located outside ofthe housing of the IEAD at a selected tissue location, said at least twoelectrodes comprising at least one cathode electrode and at least oneanode electrode, said method comprising: (a) implanting the IEAD belowthe skin surface of the patient at or near a target tissue locationselected from the group of target tissue locations comprising acupointsGV20 or GB34, and (b) enabling the IEAD to provide EA stimulation pulsesin accordance with a stimulation regimen that provides a stimulationsession having a duration of T3 minutes at a rate of once every T4minutes, where the ratio of T3/T4 is no greater than 0.05, and whereinT3 is at least 10 minutes and no greater than 60 minutes.
 20. The methodof claim 19 further including setting the stimulation pulses during astimulation session to have a duration of T1 seconds, that occur at arate of once every T2 seconds, wherein T1 is 0.1 to 2.0 milliseconds,and T2 is 67 to 1000 milliseconds.
 21. The method of claim 19 furtherincluding setting the stimulation pulses during a stimulation session tohave a duration of T1 seconds, that occur at a rate of once every T2seconds, wherein T1 is 0.1 to 2.0 milliseconds, and T2 is 8.3 to 10milliseconds.
 22. The method of claim 19 further including controllingthe electronic circuits within the IEAD to limit the instantaneouscurrent drawn from the small disc primary battery so that the outputvoltage of the primary battery does not drop more than about 11% belowthe output voltage of the primary battery when current is being drawnfrom the primary battery, where the output voltage of the primarybattery is equal to the specified nominal output voltage of the primarybattery less the voltage drop caused by the instantaneous currentflowing through the internal impedance of the primary battery.
 23. Themethod of claim 22 wherein the electronic circuitry within the IEADincludes a boost converter circuit, and wherein the method ofcontrolling the electronic circuits within the IEAD to limit theinstantaneous current drawn from the battery comprises modulating theoperation of the boost converter circuit between an ON state and an OFFstate.
 24. A method of assembling an implantable electroacupuncturedevice (IEAD) in a small, thin, hermetically-sealed, housing having amaximum linear dimension in a first plane of no more than 25 mm and amaximum linear dimension in a second plane orthogonal to the first planeof no more than 2.5 mm, the housing having at least one feed-through pinassembly radially passing through a wall of the thin housing thatisolates the feed-through pin assembly from high temperatures andresidual weld stresses that occur when the thin housing is welded shutto hermetically-seal its contents, the IEAD being adapted for use intreating Parkinson's disease or Essential Tremor of a patient, themethod comprising the steps of: (a) forming a thin housing having abottom case and a top cover plate, the top cover plate being adapted tofit over the bottom case, the bottom case having a maximum lineardimension of no more than 25 mm; (b) forming a recess in a wall of thehousing; (c) placing a feed-through assembly within the recess so that afeed-through pin of the feed-through assembly electrically passesthrough a wall of the recess at a location that is separated from wherethe wall of the housing is designed to contact the top cover plate; and(d) welding the top cover plate to the bottom case around a perimeter ofthe bottom case, thereby hermetically sealing the bottom case and topcase together.